Initial work

2020-03-04 11:25:23 -08:00
81 changed files with 7345 additions and 9795 deletions
--- a/Cargo.lock
+++ b/Cargo.lock
--- a/Cargo.toml
+++ b/Cargo.toml
@ -2,14 +2,12 @@
 name = "schala"
 version = "0.1.0"
 authors = ["greg <greg.shuflin@protonmail.com>"]
-edition = "2018"
-resolver = "2"

 [dependencies]
-getopts = "0.2.21"

 schala-repl = { path = "schala-repl" }
-schala-lang = { path = "schala-lang" }
+schala-lang = { path = "schala-lang/language" }
+partis = { path="partis" }
 # maaru-lang = { path = "maaru" }
 # rukka-lang = { path = "rukka" }
 # robo-lang = { path = "robo" }
--- a/README.md
+++ b/README.md
@ -1,44 +1,22 @@
 # Schala - a programming language meta-interpreter

 Schala is a Rust framework written to make it easy to create and experiment
-with multiple toy programming languages. It provides a cross-language REPL and
+with multipl toy programming languages. It provides a cross-language REPL and
 provisions for tokenizing text, parsing tokens, evaluating an abstract syntax
-tree, and other tasks that are common to all programming languages, as well as
-sharing state between multiple programming languages.
+tree, and other tasks that are common to all programming languages, as well as sharing state
+between multiple programming languages.

-Schala is implemented as a Rust library `schala-repl`, which provides a `Repl`
-data structure that takes in a value implementing the
-`ProgrammingLanguageInterface` trait. Individual programming language
-implementations are Rust types that implement `ProgrammingLanguageInterface`
-and store whatever persistent state is relevant to that language. 
+Schala is implemented as a Rust library `schala-repl`, which provides a
+function `start_repl`, meant to be used as entry point into a common REPL or
+non-interactive environment. Clients are expected to invoke `start_repl` with a
+vector of programming languages. Individual programming language
+implementations are Rust types that implement the
+`ProgrammingLanguageInterface` trait and store whatever persistent state is
+relevant to that language. 

-
-## Running
-
-Run schala with the normal `cargo run`. This will drop you into a REPL
-environment.  Type `:help` for more information, or type in text in any
-supported programming language (currently only `schala-lang`) to evaluate it in
-the REPL.
-
-### Examples
-
-Try running the following `schala-lang` code example in the REPL:
-
-```
->> 1 + 1
-(Total time)=> 736.368µs
-=> 2
->> fn foo(x) { x + 10 }
-(Total time)=> 772.496µs
-=> 
->> foo(0)
-(Total time)=> 593.591µs
-=> 10
->> 5 + foo(1)
-(Total time)=> 1.119916ms
-=> 16
->> 
-```
+Run schala with: `cargo run`. This will drop you into a REPL environment.  Type
+`:help` for more information, or type in text in any supported programming
+language (currently only schala-lang) to evaluate it in the REPL.

 ## History

@ -83,28 +61,35 @@ of learning how to write a programming language.

 ### General

-* http://thume.ca/2019/04/18/writing-a-compiler-in-rust/
+http://thume.ca/2019/04/18/writing-a-compiler-in-rust/

 ### Type-checking
-* https://skillsmatter.com/skillscasts/10868-inside-the-rust-compiler
-* https://www.youtube.com/watch?v=il3gD7XMdmA
-* http://dev.stephendiehl.com/fun/006_hindley_milner.html
-* https://rust-lang-nursery.github.io/rustc-guide/type-inference.html
-* https://eli.thegreenplace.net/2018/unification/
-* https://eli.thegreenplace.net/2018/type-inference/
-* http://smallcultfollowing.com/babysteps/blog/2017/03/25/unification-in-chalk-part-1/
-* http://reasonableapproximation.net/2019/05/05/hindley-milner.html
+https://skillsmatter.com/skillscasts/10868-inside-the-rust-compiler
+https://www.youtube.com/watch?v=il3gD7XMdmA
+http://dev.stephendiehl.com/fun/006_hindley_milner.html
+https://rust-lang-nursery.github.io/rustc-guide/type-inference.html
+
+https://eli.thegreenplace.net/2018/unification/
+https://eli.thegreenplace.net/2018/type-inference/
+http://smallcultfollowing.com/babysteps/blog/2017/03/25/unification-in-chalk-part-1/
+http://reasonableapproximation.net/2019/05/05/hindley-milner.html
 https://rickyhan.com/jekyll/update/2018/05/26/hindley-milner-tutorial-rust.html

 ### Evaluation
+*Understanding Computation*, Tom Stuart, O'Reilly 2013

-* _Understanding Computation_, Tom Stuart, O'Reilly 2013
-* _Basics of Compiler Design_, Torben Mogensen
+*Basics of Compiler Design*, Torben Mogensen

 ### Parsing
-* http://journal.stuffwithstuff.com/2011/03/19/pratt-parsers-expression-parsing-made-easy/
-* https://soc.github.io/languages/unified-condition-syntax
-* [Crafting Interpreters](http://www.craftinginterpreters.com/)
+http://journal.stuffwithstuff.com/2011/03/19/pratt-parsers-expression-parsing-made-easy/
+https://soc.github.io/languages/unified-condition-syntax
+
+[Crafting Interpreters](http://www.craftinginterpreters.com/)

 ### LLVM
-* http://blog.ulysse.io/2016/07/03/llvm-getting-started.html
+http://blog.ulysse.io/2016/07/03/llvm-getting-started.html
+
+###Rust resources
+https://thefullsnack.com/en/rust-for-the-web.html
+
+https://rocket.rs/guide/getting-started/
--- a/TODO.md
+++ b/TODO.md
@ -1,32 +1,4 @@
-# Immediate TODOs / General Code Cleanup
-
-## Parsing
-
-* cf. https://siraben.dev/2022/03/22/tree-sitter-linter.html write a tree-sitter parser for Schala
-
-* Create a macro system, perhaps c.f. Crystal's?
-    * Macro system should be able to implement:
-        * printf-style variadic arguments
-        * something like the Rust/Haskell `Derive` construct
-        * doing useful things with all variants of an enum 
-            * (e.g. what https://matklad.github.io//2022/03/26/self-modifying-code.html tries to solve)
-
-
-## Testing
-
-* Make an automatic (macro-based?) system for numbering compiler errors, this should be every type of error
-
-## Symbols
-
-* Add some good printf-debugging impls for SymbolTable-related items
-
-* the symbol table should probably *only* be for global definitions (maybe rename it to reflect this?)
-* dealing with variable lookup w/in functions/closures should probably happen in AST -> ReducedAST
-    * b/c that's where we go from a string name to a canonical ID (for e.g. 2nd param in 3rd enclosing scope)
-
-* In fact to prove this works, the symbol table shoudl _parallelize_ the process of checking subscopes for local items
-
-* Old notes on a plan of attack:
+# Plan of attack

 1. modify visitor so it can handle scopes
  -this is needed both to handle import scope correctly
@ -34,59 +6,66 @@

 2. Once FQSNs are aware of function parameters, most of the Rc<String> things in eval.rs can go away

-## Typechecking
+# TODO items

-* make a type to represent types rather than relying on string comparisons
-* look at https://rickyhan.com/jekyll/update/2018/05/26/hindley-milner-tutorial-rust.html
-
-## General code cleanup
-* standardize on an error type that isn't String
-* implement a visitor pattern for the use of scope_resolver
-  * maybe implement this twice: 1) the value-returning, no-default one in the haoyi blogpost,
-  * look at
-    * https://gitlab.haskell.org/ghc/ghc/wikis/pattern-synonyms
-    * the non-value-returning, default one like in rustc (cf. https://github.com/rust-unofficial/patterns/blob/master/patterns/visitor.md)
-
-
-# Longer-term Ideas
-
-## Language Syntax
-
-* the `type` declaration should have some kind of GADT-like syntax
-* syntactic sugar for typestates? (cf. https://rustype.github.io/notes/notes/rust-typestate-series/rust-typestate-part-1.html )
-* use `let` sigil to indicate a variable in a pattern explicitly:
+-use 'let' sigil in patterns for variables :

 ```
  q is MyStruct(let a, Chrono::Trigga) then {
-    // a is in scope here

  }
 ```

-* if you have a pattern-match where one variant has a variable and the other
-  lacks it instead of treating this as a type error, promote the bound variable
-  to an option type
+-idea: what if there was something like React jsx syntas built in? i.e. a way to automatically transform some kind of markup
+into a function call, cf. `<h1 prop="arg">` ->  h1(prop=arg)

-* what if there was something like React jsx syntas built in? i.e. a way to
-  automatically transform some kind of markup into a function call, cf. `<h1
-  prop="arg">` ->  h1(prop=arg)
+## General code cleanup
+- I think I can restructure the parser to get rid of most instances of expect!, at least at the beginning of a rule
+DONE -experiment with storing metadata via ItemIds on AST nodes (cf. https://rust-lang.github.io/rustc-guide/hir.html, https://github.com/rust-lang/rust/blob/master/src/librustc/hir/mod.rs )
+-implement and test open/use statements
+-implement field access
+- standardize on an error type that isn't String
+-implement a visitor pattern for the use of scope_resolver
+  - maybe implement this twice: 1) the value-returning, no-default one in the haoyi blogpost,
+  -look at https://gitlab.haskell.org/ghc/ghc/wikis/pattern-synonyms
+                                2) the non-value-returning, default one like in rustc (cf. https://github.com/rust-unofficial/patterns/blob/master/patterns/visitor.md)

-* implement and test open/use statements
+-parser error - should report subset of AST parsed *so far*
+  - what if you used python 'def' syntax to define a function? what error message makes sense here?

-* Include extensible scala-style `html"string ${var}"` string interpolations
+## Reduction
+ - make a good type for actual language builtins to avoid string comparisons

-* A neat idea for pattern matching optimization would be if you could match on
-  one of several things in a list
+## Typechecking
+
+- make a type to represent types rather than relying on string comparisons
+
+- look at https://rickyhan.com/jekyll/update/2018/05/26/hindley-milner-tutorial-rust.html
+
+- cf. the notation mentioned in the cardelli paper, the debug information for the `typechecking` pass should 
+print the generated type variable for every subexpression in an expression
+
+- think about idris-related ideas of multiple implementations of a type for an interface (+ vs * impl for monoids, for preorder/inorder/postorder for Foldable)
+
+-should have an Idris-like `cast To From` function
+
+## Schala-lang syntax
+
+-idea: the `type` declaration should have some kind of GADT-like syntax
+
+- Idea: if you have a pattern-match where one variant has a variable and the other lacks it
+instead of treating this as a type error, promote the bound variable to an option type
+
+- Include extensible scala-style html"string ${var}" string interpolations
+
+- A neat idea for pattern matching optimization would be if you could match on one of several things in a list
 ex:
-```
-if x {
+```if x {
 is (comp, LHSPat, RHSPat) if comp in ["==, "<"] -> ...
-}
-```
+}```

-* Schala should have both currying *and* default arguments!
-```
-fn a(b: Int, c:Int, d:Int = 1) -> Int
+- Schala should have both currying *and* default arguments!
+```fn a(b: Int, c:Int, d:Int = 1) -> Int
    a(1,2) : Int
    a(1,2,d=2): Int
    a(_,1,3) : Int -> Int
@ -94,49 +73,35 @@ fn a(b: Int, c:Int, d:Int = 1) -> Int
    a(_,_,_) : Int -> Int -> Int -> Int
 ```

-* scoped types - be able to define a quick enum type scoped to a function or other type for
+- scoped types - be able to define a quick enum type scoped to a function or other type for
  something, that only is meant to be used as a quick bespoke interface between
  two other things

-
 ex.
-```
-type enum {
+```type enum {
  type enum MySubVariant {
    SubVariant1, SubVariant2, etc.
    }
 Variant1(MySubVariant),
 Variant2(...),
- }
-```
-
-* inclusive/exclusive range syntax like .. vs ..=
-
-* Nameable patterns/ pattern synonyms cf. https://gitlab.haskell.org/ghc/ghc/-/wikis/pattern-synonyms
-
-
-## Typechecking
-
-* cf. the notation mentioned in the cardelli paper, the debug information for the `typechecking` pass should
-    * print the generated type variable for every subexpression in an expression
-* think about idris-related ideas of multiple implementations of a type for an interface (+ vs * impl for monoids, for preorder/inorder/postorder for Foldable)
-* should have an Idris-like `cast To From` function
-
-* something like the swift `Never` type ( https://nshipster.com/never/ ) in the stdlib
+ }```

+- inclusive/exclusive range syntax like .. vs ..=

 ## Compilation
-* look into Inkwell for rust LLVM bindings
-* https://cranelift.readthedocs.io/en/latest/?badge=latest<Paste>
+-look into Inkwell for rust LLVM bindings

-* look at https://gluon-lang.org/doc/nightly/book/embedding-api.html
+-https://cranelift.readthedocs.io/en/latest/?badge=latest<Paste>


-# Syntax Playground
+## Other links of note
+
+- https://nshipster.com/never/
+-consult http://gluon-lang.org/book/embedding-api.html
+

 ## Trying if-syntax again

-```
 //simple if expr
 if x == 10 then "a" else "z"

@ -167,7 +132,7 @@ if x {
 is Person(_, age) if age > 13 then "barmitzvah'd"
 else "foo"
 }
-```
+


 ## (OLD) Playing around with conditional syntax ideas
--- a/partis/Cargo.toml
+++ b/partis/Cargo.toml
@ -0,0 +1,9 @@
+[package]
+name = "partis"
+version = "0.1.0"
+authors = ["greg <greg.shuflin@protonmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
--- a/partis/src/lib.rs
+++ b/partis/src/lib.rs
@ -0,0 +1,17 @@
+struct ParseError { }
+
+enum ParseResult<'a, T> {
+  Success(T, &'a str),
+  Failure(ParseError),
+  Incomplete,
+}
+
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        assert_eq!(2 + 2, 4);
+    }
+
+}
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@ -1,2 +0,0 @@
-[toolchain]
-channel = "nightly"
--- a/rustfmt.toml
+++ b/rustfmt.toml
@ -1,8 +0,0 @@
-
-max_width = 110
-use_small_heuristics = "max"
-imports_indent = "block"
-imports_granularity = "crate"
-group_imports = "stdexternalcrate"
-match_arm_blocks = false
-where_single_line = true
--- a/schala-lang/Cargo.toml
+++ b/schala-lang/Cargo.toml
@ -1,27 +0,0 @@
-[package]
-name = "schala-lang"
-version = "0.1.0"
-authors = ["greg <greg.shuflin@protonmail.com>"]
-edition = "2021"
-
-[dependencies]
-itertools = "0.10"
-take_mut = "0.2.2"
-failure = "0.1.5"
-ena = "0.11.0"
-stopwatch = "0.0.7"
-derivative = "2.2.0"
-colored = "1.8"
-radix_trie = "0.1.5"
-assert_matches = "1.5"
-#peg = "0.7.0"
-peg = "0.8.1"
-nom = "7.1.0"
-nom_locate = "4.0.0"
-
-
-schala-repl = { path = "../schala-repl" }
-
-[dev-dependencies]
-test-case = "1.2.0"
-pretty_assertions = "1.0.0"
--- a/schala-lang/codegen/Cargo.toml
+++ b/schala-lang/codegen/Cargo.toml
@ -0,0 +1,12 @@
+[package]
+name = "schala-lang-codegen"
+version = "0.1.0"
+authors = ["greg <greg.shuflin@protonmail.com>"]
+edition = "2018"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+syn = { version = "0.15.12", features = ["full", "extra-traits", "fold"] }
+quote = "0.6.8"
--- a/schala-lang/codegen/src/lib.rs
+++ b/schala-lang/codegen/src/lib.rs
@ -0,0 +1,54 @@
+#![feature(box_patterns)]
+#![recursion_limit="128"]
+extern crate proc_macro;
+#[macro_use]
+extern crate quote;
+#[macro_use]
+extern crate syn;
+
+use self::proc_macro::TokenStream;
+use self::syn::fold::Fold;
+
+struct RecursiveDescentFn {
+}
+
+impl Fold for RecursiveDescentFn {
+  fn fold_item_fn(&mut self, mut i: syn::ItemFn) -> syn::ItemFn {
+    let box block = i.block;
+    let ref ident = i.ident;
+
+    let new_block: syn::Block = parse_quote! {
+      {
+        let next_token_before_parse = self.token_handler.peek();
+        let record = ParseRecord {
+          production_name: stringify!(#ident).to_string(),
+          next_token: format!("{}", next_token_before_parse.to_string_with_metadata()),
+          level: self.parse_level,
+        };
+        self.parse_level += 1;
+        self.parse_record.push(record);
+        let result = { #block };
+
+        if self.parse_level != 0 {
+          self.parse_level -= 1;
+        }
+
+        result.map_err(|mut parse_error: ParseError| {
+          parse_error.production_name = Some(stringify!(#ident).to_string());
+          parse_error
+        })
+      }
+    };
+    i.block = Box::new(new_block);
+    i
+  }
+}
+
+#[proc_macro_attribute]
+pub fn recursive_descent_method(_attr: TokenStream, item: TokenStream) -> TokenStream {
+
+  let input: syn::ItemFn = parse_macro_input!(item as syn::ItemFn);
+  let mut folder = RecursiveDescentFn {};
+  let output = folder.fold_item_fn(input);
+  TokenStream::from(quote!(#output))
+}
--- a/schala-lang/language/Cargo.toml
+++ b/schala-lang/language/Cargo.toml
@ -0,0 +1,20 @@
+[package]
+name = "schala-lang"
+version = "0.1.0"
+authors = ["greg <greg.shuflin@protonmail.com>"]
+edition = "2018"
+
+[dependencies]
+itertools = "0.8.0"
+take_mut = "0.2.2"
+maplit = "1.0.1"
+lazy_static = "1.3.0"
+failure = "0.1.5"
+ena = "0.11.0"
+stopwatch = "0.0.7"
+derivative = "1.0.3"
+colored = "1.8"
+radix_trie = "0.1.5"
+
+schala-lang-codegen = { path = "../codegen" }
+schala-repl = { path = "../../schala-repl" }
--- a/schala-lang/language/src/ast.rs
+++ b/schala-lang/language/src/ast.rs
@ -0,0 +1,307 @@
+use std::rc::Rc;
+
+use crate::derivative::Derivative;
+
+mod walker;
+mod visitor;
+mod visitor_test;
+mod operators;
+pub use operators::*;
+pub use visitor::ASTVisitor;
+pub use walker::walk_ast;
+
+/// An abstract identifier for an AST node
+#[derive(Debug, PartialEq, Eq, Hash, Clone)]
+pub struct ItemId {
+  idx: u32,
+}
+
+impl ItemId {
+  fn new(n: u32) -> ItemId {
+    ItemId { idx: n }
+  }
+}
+
+pub struct ItemIdStore {
+  last_idx: u32
+}
+
+impl ItemIdStore {
+  pub fn new() -> ItemIdStore {
+    ItemIdStore { last_idx: 0 }
+  }
+  /// Always returns an ItemId with internal value zero
+  #[cfg(test)]
+  pub fn new_id() -> ItemId {
+    ItemId { idx: 0 }
+  }
+
+  /// This limits the size of the AST to 2^32 tree elements
+  pub fn fresh(&mut self) -> ItemId {
+    let idx = self.last_idx;
+    self.last_idx += 1;
+    ItemId::new(idx)
+  }
+}
+
+#[derive(Derivative, Debug)]
+#[derivative(PartialEq)]
+pub struct AST {
+  #[derivative(PartialEq="ignore")]
+  pub id: ItemId,
+  pub statements: Vec<Statement>
+}
+
+#[derive(Derivative, Debug, Clone)]
+#[derivative(PartialEq)]
+pub struct Statement {
+  #[derivative(PartialEq="ignore")]
+  pub id: ItemId,
+  pub kind: StatementKind,
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum StatementKind {
+  Expression(Expression),
+  Declaration(Declaration),
+  Import(ImportSpecifier),
+  Module(ModuleSpecifier),
+}
+
+pub type Block = Vec<Statement>;
+pub type ParamName = Rc<String>;
+
+#[derive(Debug, Derivative, Clone)]
+#[derivative(PartialEq)]
+pub struct QualifiedName {
+  #[derivative(PartialEq="ignore")]
+  pub id: ItemId,
+  pub components: Vec<Rc<String>>,
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct FormalParam {
+  pub name: ParamName,
+  pub default: Option<Expression>,
+  pub anno: Option<TypeIdentifier>
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum Declaration {
+  FuncSig(Signature),
+  FuncDecl(Signature, Block),
+  TypeDecl {
+    name: TypeSingletonName,
+    body: TypeBody,
+    mutable: bool
+  },
+  //TODO this needs to be more sophisticated
+  TypeAlias {
+    alias: Rc<String>,
+    original: Rc<String>,
+  },
+  Binding {
+    name: Rc<String>,
+    constant: bool,
+    type_anno: Option<TypeIdentifier>,
+    expr: Expression,
+  },
+  Impl {
+    type_name: TypeIdentifier,
+    interface_name: Option<TypeSingletonName>,
+    block: Vec<Declaration>,
+  },
+  Interface {
+    name: Rc<String>,
+    signatures: Vec<Signature>
+  }
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct Signature {
+  pub name: Rc<String>,
+  pub operator: bool,
+  pub params: Vec<FormalParam>,
+  pub type_anno: Option<TypeIdentifier>,
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct TypeBody(pub Vec<Variant>);
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum Variant {
+  UnitStruct(Rc<String>),
+  TupleStruct(Rc<String>, Vec<TypeIdentifier>),
+  Record {
+    name: Rc<String>,
+    members: Vec<(Rc<String>, TypeIdentifier)>,
+  }
+}
+
+#[derive(Debug, Derivative, Clone)]
+#[derivative(PartialEq)]
+pub struct Expression {
+  #[derivative(PartialEq="ignore")]
+  pub id: ItemId,
+  pub kind: ExpressionKind,
+  pub type_anno: Option<TypeIdentifier>
+}
+
+impl Expression {
+  pub fn new(id: ItemId, kind: ExpressionKind) -> Expression {
+    Expression { id, kind, type_anno: None }
+  }
+
+  pub fn with_anno(id: ItemId, kind: ExpressionKind, type_anno: TypeIdentifier) -> Expression {
+    Expression { id, kind, type_anno: Some(type_anno) }
+  }
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum TypeIdentifier {
+  Tuple(Vec<TypeIdentifier>),
+  Singleton(TypeSingletonName)
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct TypeSingletonName {
+  pub name: Rc<String>,
+  pub params: Vec<TypeIdentifier>,
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum ExpressionKind {
+  NatLiteral(u64),
+  FloatLiteral(f64),
+  StringLiteral(Rc<String>),
+  BoolLiteral(bool),
+  BinExp(BinOp, Box<Expression>, Box<Expression>),
+  PrefixExp(PrefixOp, Box<Expression>),
+  TupleLiteral(Vec<Expression>),
+  Value(QualifiedName),
+  NamedStruct {
+    name: QualifiedName,
+    fields: Vec<(Rc<String>, Expression)>,
+  },
+  Call {
+    f: Box<Expression>,
+    arguments: Vec<InvocationArgument>,
+  },
+  Index {
+    indexee: Box<Expression>,
+    indexers: Vec<Expression>,
+  },
+  IfExpression {
+    discriminator: Option<Box<Expression>>,
+    body: Box<IfExpressionBody>,
+  },
+  WhileExpression {
+    condition: Option<Box<Expression>>,
+    body: Block,
+  },
+  ForExpression {
+    enumerators: Vec<Enumerator>,
+    body: Box<ForBody>,
+  },
+  Lambda {
+    params: Vec<FormalParam>,
+    type_anno: Option<TypeIdentifier>,
+    body: Block,
+  },
+  ListLiteral(Vec<Expression>),
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum InvocationArgument {
+  Positional(Expression),
+  Keyword {
+    name: Rc<String>,
+    expr: Expression,
+  },
+  Ignored
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum IfExpressionBody {
+  SimpleConditional {
+    then_case: Block,
+    else_case: Option<Block>
+  },
+  SimplePatternMatch {
+    pattern: Pattern,
+    then_case: Block,
+    else_case: Option<Block>
+  },
+  CondList(Vec<ConditionArm>)
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct ConditionArm {
+  pub condition: Condition,
+  pub guard: Option<Expression>,
+  pub body: Block,
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum Condition {
+  Pattern(Pattern),
+  TruncatedOp(BinOp, Expression),
+  Expression(Expression),
+  Else,
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum Pattern {
+  Ignored,
+  TuplePattern(Vec<Pattern>),
+  Literal(PatternLiteral),
+  TupleStruct(QualifiedName, Vec<Pattern>),
+  Record(QualifiedName, Vec<(Rc<String>, Pattern)>),
+  VarOrName(QualifiedName),
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum PatternLiteral {
+  NumPattern {
+    neg: bool,
+    num: ExpressionKind,
+  },
+  StringPattern(Rc<String>),
+  BoolPattern(bool),
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct Enumerator {
+  pub id: Rc<String>,
+  pub generator: Expression,
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum ForBody {
+  MonadicReturn(Expression),
+  StatementBlock(Block),
+}
+
+#[derive(Debug, Derivative, Clone)]
+#[derivative(PartialEq)]
+pub struct ImportSpecifier {
+  #[derivative(PartialEq="ignore")]
+  pub id: ItemId,
+  pub path_components: Vec<Rc<String>>,
+  pub imported_names: ImportedNames
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum ImportedNames {
+  All,
+  LastOfPath,
+  List(Vec<Rc<String>>)
+}
+
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct ModuleSpecifier {
+  pub name: Rc<String>,
+  pub contents: Vec<Statement>,
+}
+
--- a/schala-lang/language/src/ast/operators.rs
+++ b/schala-lang/language/src/ast/operators.rs
@ -0,0 +1,108 @@
+use std::rc::Rc;
+use std::str::FromStr;
+
+use crate::tokenizing::TokenKind;
+use crate::builtin::Builtin;
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct PrefixOp {
+  sigil: Rc<String>,
+  pub builtin: Option<Builtin>,
+}
+
+impl PrefixOp {
+  #[allow(dead_code)]
+  pub fn sigil(&self) -> &Rc<String> {
+    &self.sigil
+  }
+  pub fn is_prefix(op: &str) -> bool {
+    match op {
+      "+" => true,
+      "-" => true,
+      "!" => true,
+      _ => false
+    }
+  }
+}
+
+impl FromStr for PrefixOp {
+  type Err = ();
+
+  fn from_str(s: &str) -> Result<Self, Self::Err> {
+    use Builtin::*;
+
+    let builtin = match s {
+      "+" => Ok(Increment),
+      "-" => Ok(Negate),
+      "!" => Ok(BooleanNot),
+      _ => Err(())
+    };
+
+    builtin.map(|builtin| PrefixOp { sigil: Rc::new(s.to_string()), builtin: Some(builtin) })
+  }
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct BinOp {
+  sigil: Rc<String>,
+  pub builtin: Option<Builtin>,
+}
+
+impl BinOp {
+  pub fn from_sigil(sigil: &str) -> BinOp {
+    let builtin = Builtin::from_str(sigil).ok();
+    BinOp { sigil: Rc::new(sigil.to_string()), builtin }
+  }
+  pub fn sigil(&self) -> &Rc<String> {
+    &self.sigil
+  }
+  pub fn from_sigil_token(tok: &TokenKind) -> Option<BinOp> {
+    let s = token_kind_to_sigil(tok)?;
+    Some(BinOp::from_sigil(s))
+  }
+
+  pub fn min_precedence() -> i32 {
+    i32::min_value()
+  }
+  pub fn get_precedence_from_token(op_tok: &TokenKind) -> Option<i32> {
+    let s = token_kind_to_sigil(op_tok)?;
+    Some(binop_precedences(s))
+  }
+}
+
+fn token_kind_to_sigil<'a>(tok: &'a TokenKind) -> Option<&'a str> {
+  use self::TokenKind::*;
+  Some(match tok {
+    Operator(op) => op.as_str(),
+    Period => ".",
+    Pipe => "|",
+    Slash => "/",
+    LAngleBracket => "<",
+    RAngleBracket => ">",
+    Equals => "=",
+    _ => return None
+  })
+}
+
+fn binop_precedences(s: &str) -> i32 {
+  let default = 10_000_000;
+  match s {
+    "+" => 10,
+    "-" => 10,
+    "*" =>  20,
+    "/" =>  20,
+    "%" =>  20,
+    "++" => 30,
+    "^" =>  30,
+    "&" =>  20,
+    "|" => 20,
+    ">" => 20,
+    ">=" => 20,
+    "<" =>  20,
+    "<=" => 20,
+    "==" => 40,
+    "=" =>  10,
+    "<=>" => 30,
+    _ => default,
+  }
+}
--- a/schala-lang/language/src/ast/visitor.rs
+++ b/schala-lang/language/src/ast/visitor.rs
@ -0,0 +1,41 @@
+use std::rc::Rc;
+use crate::ast::*;
+
+//TODO maybe these functions should take closures that return a KeepRecursing | StopHere type,
+//or a tuple of (T, <that type>)
+
+pub trait ASTVisitor: Sized {
+  fn ast(&mut self, _ast: &AST) {}
+  fn block(&mut self, _statements: &Vec<Statement>) {}
+  fn statement(&mut self, _statement: &Statement) {}
+  fn declaration(&mut self, _declaration: &Declaration) {}
+  fn signature(&mut self, _signature: &Signature) {}
+  fn type_declaration(&mut self, _name: &TypeSingletonName, _body: &TypeBody, _mutable: bool) {}
+  fn type_alias(&mut self, _alias: &Rc<String>, _original: &Rc<String>) {}
+  fn binding(&mut self, _name: &Rc<String>, _constant: bool, _type_anno: Option<&TypeIdentifier>, _expr: &Expression) {}
+  fn implemention(&mut self, _type_name: &TypeIdentifier, _interface_name: Option<&TypeSingletonName>, _block: &Vec<Declaration>) {}
+  fn interface(&mut self, _name: &Rc<String>, _signatures: &Vec<Signature>) {}
+  fn expression(&mut self, _expression: &Expression) {}
+  fn expression_kind(&mut self, _kind: &ExpressionKind) {}
+  fn type_annotation(&mut self, _type_anno: Option<&TypeIdentifier>) {}
+  fn named_struct(&mut self, _name: &QualifiedName, _fields: &Vec<(Rc<String>, Expression)>) {}
+  fn call(&mut self, _f: &Expression, _arguments: &Vec<InvocationArgument>) {}
+  fn index(&mut self, _indexee: &Expression, _indexers: &Vec<Expression>) {}
+  fn if_expression(&mut self, _discrim: Option<&Expression>, _body: &IfExpressionBody) {}
+  fn condition_arm(&mut self, _arm: &ConditionArm) {}
+  fn while_expression(&mut self, _condition: Option<&Expression>, _body: &Block) {}
+  fn for_expression(&mut self, _enumerators: &Vec<Enumerator>, _body: &ForBody) {}
+  fn lambda(&mut self, _params: &Vec<FormalParam>, _type_anno: Option<&TypeIdentifier>, _body: &Block) {}
+  fn invocation_argument(&mut self, _arg: &InvocationArgument) {}
+  fn formal_param(&mut self, _param: &FormalParam) {}
+  fn import(&mut self, _import: &ImportSpecifier) {}
+  fn module(&mut self, _module: &ModuleSpecifier) {}
+  fn qualified_name(&mut self, _name: &QualifiedName) {}
+  fn nat_literal(&mut self, _n: u64) {}
+  fn float_literal(&mut self, _f: f64) {}
+  fn string_literal(&mut self, _s: &Rc<String>) {}
+  fn bool_literal(&mut self, _b: bool) {}
+  fn binexp(&mut self, _op: &BinOp, _lhs: &Expression, _rhs: &Expression) {}
+  fn prefix_exp(&mut self, _op: &PrefixOp, _arg: &Expression) {}
+  fn pattern(&mut self, _pat: &Pattern) {}
+}
--- a/schala-lang/language/src/ast/visitor_test.rs
+++ b/schala-lang/language/src/ast/visitor_test.rs
@ -0,0 +1,41 @@
+#![cfg(test)]
+
+use crate::ast::visitor::ASTVisitor;
+use crate::ast::walker;
+use crate::util::quick_ast;
+
+struct Tester {
+  count: u64,
+  float_count: u64
+}
+
+impl ASTVisitor for Tester {
+  fn nat_literal(&mut self, _n: u64) {
+    self.count += 1;
+  }
+  fn float_literal(&mut self, _f: f64) {
+    self.float_count += 1;
+  }
+}
+
+
+#[test]
+fn foo() {
+  let mut tester = Tester { count: 0, float_count: 0 };
+  let (ast, _) = quick_ast(r#"
+import gragh
+
+let a = 20 + 84
+let b = 28 + 1 + 2 + 2.0
+fn heh() {
+  let m = 9
+
+}
+
+"#);
+
+  walker::walk_ast(&mut tester, &ast);
+
+  assert_eq!(tester.count, 6);
+  assert_eq!(tester.float_count, 1);
+}
--- a/schala-lang/language/src/ast/walker.rs
+++ b/schala-lang/language/src/ast/walker.rs
@ -0,0 +1,269 @@
+#![allow(dead_code)]
+use std::rc::Rc;
+use crate::ast::*;
+use crate::ast::visitor::ASTVisitor;
+use crate::util::deref_optional_box;
+
+pub fn walk_ast<V: ASTVisitor>(v: &mut V, ast: &AST) {
+  v.ast(ast);
+  walk_block(v, &ast.statements);
+}
+
+fn walk_block<V: ASTVisitor>(v: &mut V, block: &Vec<Statement>) {
+  for s in block {
+    v.statement(s);
+    statement(v, s);
+  }
+}
+
+fn statement<V: ASTVisitor>(v: &mut V, statement: &Statement) {
+  use StatementKind::*;
+  match statement.kind {
+    Expression(ref expr) => {
+      v.expression(expr);
+      expression(v, expr);
+    },
+    Declaration(ref decl) => {
+      v.declaration(decl);
+      declaration(v, decl);
+    },
+    Import(ref import_spec) => v.import(import_spec),
+    Module(ref module_spec) => {
+      v.module(module_spec);
+      walk_block(v, &module_spec.contents);
+    }
+  }
+}
+
+fn declaration<V: ASTVisitor>(v: &mut V, decl: &Declaration) {
+  use Declaration::*;
+  match decl {
+    FuncSig(sig) => {
+      v.signature(&sig);
+      signature(v, &sig);
+    },
+    FuncDecl(sig, block) => {
+      v.signature(&sig);
+      v.block(&block);
+      walk_block(v, block);
+    },
+    TypeDecl { name, body, mutable  } => v.type_declaration(name, body, *mutable),
+    TypeAlias { alias, original} => v.type_alias(alias, original), 
+    Binding { name, constant, type_anno, expr } => {
+      v.binding(name, *constant, type_anno.as_ref(), expr);
+      v.type_annotation(type_anno.as_ref());
+      v.expression(&expr);
+      expression(v, &expr);
+    },
+    Impl { type_name, interface_name, block } => {
+      v.implemention(type_name, interface_name.as_ref(), block);
+    }
+    Interface { name, signatures } => v.interface(name, signatures),
+  }
+}
+
+fn signature<V: ASTVisitor>(v: &mut V, signature: &Signature) {
+  for p in signature.params.iter() {
+    v.formal_param(p);
+  }
+  v.type_annotation(signature.type_anno.as_ref());
+  for p in signature.params.iter() {
+    formal_param(v, p);
+  }
+}
+
+fn expression<V: ASTVisitor>(v: &mut V, expression: &Expression) {
+  v.expression_kind(&expression.kind);
+  v.type_annotation(expression.type_anno.as_ref());
+  expression_kind(v, &expression.kind);
+}
+
+
+fn call<V: ASTVisitor>(v: &mut V, f: &Expression, args: &Vec<InvocationArgument>) {
+  v.expression(f);
+  expression(v, f);
+  for arg in args.iter() {
+    v.invocation_argument(arg);
+    invocation_argument(v, arg);
+  }
+}
+
+fn invocation_argument<V: ASTVisitor>(v: &mut V, arg: &InvocationArgument) {
+  use InvocationArgument::*;
+  match arg {
+    Positional(expr) => {
+      v.expression(expr);
+      expression(v, expr);
+    },
+    Keyword { expr, .. } => {
+      v.expression(expr);
+      expression(v, expr);
+    },
+    Ignored => (),
+  }
+}
+
+fn index<V: ASTVisitor>(v: &mut V, indexee: &Expression, indexers: &Vec<Expression>) {
+  v.expression(indexee);
+  for i in indexers.iter() {
+    v.expression(i);
+  }
+}
+
+fn named_struct<V: ASTVisitor>(v: &mut V, n: &QualifiedName, fields: &Vec<(Rc<String>, Expression)>) {
+  v.qualified_name(n);
+  for (_, expr) in fields.iter() {
+    v.expression(expr);
+  }
+}
+
+fn lambda<V: ASTVisitor>(v: &mut V, params: &Vec<FormalParam>, type_anno: Option<&TypeIdentifier>, body: &Block) {
+  for param in params {
+    v.formal_param(param);
+    formal_param(v, param);
+  }
+  v.type_annotation(type_anno);
+  v.block(body);
+  walk_block(v, body);
+}
+
+fn formal_param<V: ASTVisitor>(v: &mut V, param: &FormalParam) {
+  param.default.as_ref().map(|p| {
+    v.expression(p);
+    expression(v, p);
+  });
+  v.type_annotation(param.anno.as_ref());
+}
+
+fn expression_kind<V: ASTVisitor>(v: &mut V, expression_kind: &ExpressionKind) {
+  use ExpressionKind::*;
+  match expression_kind {
+    NatLiteral(n) => v.nat_literal(*n),
+    FloatLiteral(f) => v.float_literal(*f),
+    StringLiteral(s) => v.string_literal(s),
+    BoolLiteral(b) => v.bool_literal(*b),
+    BinExp(op, lhs, rhs) => {
+      v.binexp(op, lhs, rhs);
+      expression(v, lhs);
+      expression(v, rhs);
+    },
+    PrefixExp(op, arg) => {
+      v.prefix_exp(op, arg);
+      expression(v, arg);
+    }
+    TupleLiteral(exprs) => {
+      for expr in exprs {
+        v.expression(expr);
+        expression(v, expr);
+      }
+    },
+    Value(name) => v.qualified_name(name),
+    NamedStruct { name, fields } => {
+      v.named_struct(name, fields);
+      named_struct(v, name, fields);
+    }
+    Call { f, arguments } => {
+      v.call(f, arguments);
+      call(v, f, arguments);
+    },
+    Index { indexee, indexers } => {
+      v.index(indexee, indexers);
+      index(v, indexee, indexers);
+    },
+    IfExpression { discriminator, body } => {
+      v.if_expression(deref_optional_box(discriminator), body);
+      discriminator.as_ref().map(|d| expression(v, d));
+      if_expression_body(v, body);
+    },
+    WhileExpression { condition, body } => v.while_expression(deref_optional_box(condition), body),
+    ForExpression { enumerators, body } => v.for_expression(enumerators, body),
+    Lambda { params , type_anno, body } => {
+      v.lambda(params, type_anno.as_ref(), body);
+      lambda(v, params, type_anno.as_ref(), body);
+    },
+    ListLiteral(exprs) => {
+      for expr in exprs {
+        v.expression(expr);
+        expression(v, expr);
+      }
+    },
+  }
+}
+
+fn if_expression_body<V: ASTVisitor>(v: &mut V, body: &IfExpressionBody) {
+  use IfExpressionBody::*;
+  match body {
+    SimpleConditional { then_case, else_case } => {
+      walk_block(v, then_case);
+      else_case.as_ref().map(|block| walk_block(v, block));
+    },
+    SimplePatternMatch { pattern, then_case, else_case } => {
+      v.pattern(pattern);
+      walk_pattern(v, pattern);
+      walk_block(v, then_case);
+      else_case.as_ref().map(|block| walk_block(v, block));
+    },
+    CondList(arms) => {
+      for arm in arms {
+        v.condition_arm(arm);
+        condition_arm(v, arm);
+      }
+    }
+  }
+}
+
+fn condition_arm<V: ASTVisitor>(v: &mut V, arm: &ConditionArm) {
+  use Condition::*;
+  v.condition_arm(arm);
+  match arm.condition {
+    Pattern(ref pat) => {
+      v.pattern(pat);
+      walk_pattern(v, pat);
+    },
+    TruncatedOp(ref _binop, ref expr) => {
+      v.expression(expr);
+      expression(v, expr);
+    },
+    Expression(ref expr) => {
+      v.expression(expr);
+      expression(v, expr);
+    },
+    _ => ()
+  }
+  arm.guard.as_ref().map(|guard| {
+    v.expression(guard);
+    expression(v, guard);
+  });
+  v.block(&arm.body);
+  walk_block(v, &arm.body);
+}
+
+fn walk_pattern<V: ASTVisitor>(v: &mut V, pat: &Pattern) {
+  use Pattern::*;
+  match pat {
+    TuplePattern(patterns) => {
+      for pat in patterns {
+        v.pattern(pat);
+        walk_pattern(v, pat);
+      }
+    },
+    TupleStruct(qualified_name, patterns) => {
+      v.qualified_name(qualified_name);
+      for pat in patterns {
+        v.pattern(pat);
+        walk_pattern(v, pat);
+      }
+    },
+    Record(qualified_name, name_and_patterns) => {
+      v.qualified_name(qualified_name);
+      for (_, pat) in name_and_patterns {
+        v.pattern(pat);
+        walk_pattern(v, pat);
+      }
+    },
+    VarOrName(qualified_name) => {
+      v.qualified_name(qualified_name);
+    },
+    _ => ()
+  }
+}
--- a/schala-lang/language/src/builtin.rs
+++ b/schala-lang/language/src/builtin.rs
@ -0,0 +1,102 @@
+use std::str::FromStr;
+
+use crate::typechecking::{TypeConst, Type};
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum Builtin {
+  Add,
+  Increment,
+  Subtract,
+  Negate,
+  Multiply,
+  Divide,
+  Quotient,
+  Modulo,
+  Exponentiation,
+  BitwiseAnd,
+  BitwiseOr,
+  BooleanAnd,
+  BooleanOr,
+  BooleanNot,
+  Equality,
+  LessThan,
+  LessThanOrEqual,
+  GreaterThan,
+  GreaterThanOrEqual,
+  Comparison,
+  FieldAccess,
+  IOPrint,
+  IOPrintLn,
+  IOGetLine,
+  Assignment,
+  Concatenate,
+}
+
+impl Builtin {
+  pub fn get_type(&self) -> Type {
+    use Builtin::*;
+    match self {
+      Add => ty!(Nat -> Nat -> Nat),
+      Subtract => ty!(Nat -> Nat -> Nat),
+      Multiply => ty!(Nat -> Nat -> Nat),
+      Divide => ty!(Nat -> Nat -> Float),
+      Quotient => ty!(Nat -> Nat -> Nat),
+      Modulo => ty!(Nat -> Nat -> Nat),
+      Exponentiation => ty!(Nat -> Nat -> Nat),
+      BitwiseAnd => ty!(Nat -> Nat -> Nat),
+      BitwiseOr => ty!(Nat -> Nat -> Nat),
+      BooleanAnd => ty!(Bool -> Bool -> Bool),
+      BooleanOr => ty!(Bool -> Bool -> Bool),
+      BooleanNot => ty!(Bool -> Bool),
+      Equality => ty!(Nat -> Nat -> Bool),
+      LessThan => ty!(Nat -> Nat -> Bool),
+      LessThanOrEqual => ty!(Nat -> Nat -> Bool),
+      GreaterThan => ty!(Nat -> Nat -> Bool),
+      GreaterThanOrEqual => ty!(Nat -> Nat -> Bool),
+      Comparison => ty!(Nat -> Nat -> Ordering),
+      FieldAccess => ty!(Unit),
+      IOPrint => ty!(Unit),
+      IOPrintLn => ty!(Unit) ,
+      IOGetLine => ty!(StringT),
+      Assignment => ty!(Unit),
+      Concatenate => ty!(StringT -> StringT -> StringT),
+      Increment => ty!(Nat -> Int),
+      Negate => ty!(Nat -> Int)
+    }
+  }
+}
+
+impl FromStr for Builtin {
+  type Err = ();
+
+  fn from_str(s: &str) -> Result<Self, Self::Err> {
+    use Builtin::*;
+    Ok(match s {
+      "+" => Add,
+      "-" => Subtract,
+      "*" => Multiply,
+      "/" => Divide,
+      "quot" => Quotient,
+      "%" => Modulo,
+      "++" => Concatenate,
+      "^" =>  Exponentiation,
+      "&" => BitwiseAnd,
+      "&&" => BooleanAnd,
+      "|" => BitwiseOr,
+      "||" => BooleanOr,
+      "!" => BooleanNot,
+      ">" => GreaterThan,
+      ">=" => GreaterThanOrEqual,
+      "<" => LessThan,
+      "<=" => LessThanOrEqual,
+      "==" => Equality,
+      "=" => Assignment,
+      "<=>" => Comparison,
+      "." => FieldAccess,
+      "print" => IOPrint,
+      "println" => IOPrintLn,
+      "getline" => IOGetLine,
+      _ => return Err(())
+    })
+  }
+}
--- a/schala-lang/language/src/debugging.rs
+++ b/schala-lang/language/src/debugging.rs
@ -0,0 +1,10 @@
+use crate::ast::*;
+
+impl AST {
+  pub fn compact_debug(&self) -> String {
+    format!("{:?}", self)
+  }
+  pub fn expanded_debug(&self) -> String {
+    format!("{:#?}", self)
+  }
+}
--- a/schala-lang/language/src/eval.rs
+++ b/schala-lang/language/src/eval.rs
@ -0,0 +1,455 @@
+use std::rc::Rc;
+use std::fmt::Write;
+use std::io;
+
+use itertools::Itertools;
+
+use crate::schala::SymbolTableHandle;
+use crate::util::ScopeStack;
+use crate::reduced_ast::{BoundVars, ReducedAST, Stmt, Expr, Lit, Func, Alternative, Subpattern};
+use crate::symbol_table::{SymbolSpec, Symbol, SymbolTable, FullyQualifiedSymbolName};
+use crate::builtin::Builtin;
+
+mod test;
+
+pub struct State<'a> {
+  values: ScopeStack<'a, Rc<String>, ValueEntry>,
+}
+
+impl<'a> State<'a> {
+  pub fn new() -> State<'a> {
+    let values = ScopeStack::new(Some(format!("global")));
+    State { values }
+  }
+
+  pub fn debug_print(&self) -> String {
+    format!("Values: {:?}", self.values)
+  }
+
+  fn new_frame(&'a self, items: &'a Vec<Node>, bound_vars: &BoundVars) -> State<'a> {
+    let mut inner_state = State {
+      values: self.values.new_scope(None),
+    };
+    for (bound_var, val) in bound_vars.iter().zip(items.iter()) {
+      if let Some(bv) = bound_var.as_ref() {
+        inner_state.values.insert(bv.clone(), ValueEntry::Binding { constant: true, val: val.clone() });
+      }
+    }
+    inner_state
+  }
+}
+
+#[derive(Debug, Clone)]
+enum Node {
+  Expr(Expr),
+  PrimObject {
+    name: Rc<String>,
+    tag: usize,
+    items: Vec<Node>,
+  },
+  PrimTuple {
+    items: Vec<Node>
+  }
+}
+
+fn paren_wrapped_vec(terms: impl Iterator<Item=String>) -> String {
+  let mut buf = String::new();
+  write!(buf, "(").unwrap();
+  for term in terms.map(|e| Some(e)).intersperse(None) {
+    match term {
+      Some(e) => write!(buf, "{}", e).unwrap(),
+      None => write!(buf, ", ").unwrap(),
+    };
+  }
+  write!(buf, ")").unwrap();
+  buf
+}
+
+
+impl Node {
+  fn to_repl(&self) -> String {
+    match self {
+      Node::Expr(e) => e.to_repl(),
+      Node::PrimObject { name, items, .. } if items.len() == 0 => format!("{}", name),
+      Node::PrimObject { name, items, .. } => format!("{}{}", name, paren_wrapped_vec(items.iter().map(|x| x.to_repl()))),
+      Node::PrimTuple { items } => format!("{}", paren_wrapped_vec(items.iter().map(|x| x.to_repl()))),
+    }
+  }
+  fn is_true(&self) -> bool {
+    match self {
+      Node::Expr(Expr::Lit(crate::reduced_ast::Lit::Bool(true))) => true,
+      _ => false,
+    }
+  }
+}
+
+#[derive(Debug)]
+enum ValueEntry {
+  Binding {
+    constant: bool,
+    val: /*FullyEvaluatedExpr*/ Node, //TODO make this use a subtype to represent fully evaluatedness
+  }
+}
+
+type EvalResult<T> = Result<T, String>;
+
+impl Expr {
+  fn to_node(self) -> Node {
+    Node::Expr(self)
+  }
+  fn to_repl(&self) -> String {
+    use self::Lit::*;
+    use self::Func::*;
+
+    match self {
+      Expr::Lit(ref l) => match l {
+        Nat(n) => format!("{}", n),
+        Int(i) => format!("{}", i),
+        Float(f) => format!("{}", f),
+        Bool(b) => format!("{}", b),
+        StringLit(s) => format!("\"{}\"", s),
+      },
+      Expr::Func(f) => match f {
+        BuiltIn(builtin) => format!("<built-in function '{:?}'>", builtin),
+        UserDefined { name: None, .. } => format!("<function>"),
+        UserDefined { name: Some(name), .. } => format!("<function '{}'>", name),
+      },
+      Expr::Constructor { type_name, arity, .. } => {
+        format!("<constructor for `{}` arity {}>", type_name, arity)
+      },
+      Expr::Tuple(exprs) => paren_wrapped_vec(exprs.iter().map(|x| x.to_repl())),
+      _ => format!("{:?}", self),
+    }
+  }
+
+  fn replace_conditional_target_sigil(self, replacement: &Expr) -> Expr {
+    use self::Expr::*;
+
+    match self {
+      ConditionalTargetSigilValue => replacement.clone(),
+      Unit | Lit(_) | Func(_) | Sym(_) | Constructor { .. } |
+       CaseMatch { .. } | UnimplementedSigilValue | ReductionError(_) => self,
+      Tuple(exprs) => Tuple(exprs.into_iter().map(|e| e.replace_conditional_target_sigil(replacement)).collect()),
+      Call { f, args } => {
+        let new_args = args.into_iter().map(|e| e.replace_conditional_target_sigil(replacement)).collect();
+        Call { f, args: new_args }
+      },
+      Conditional { .. } => panic!("Dunno if I need this, but if so implement"),
+      Assign { .. } => panic!("I'm pretty sure I don't need this"),
+    }
+  }
+}
+
+impl<'a> State<'a> {
+  pub fn evaluate(&mut self, ast: ReducedAST, repl: bool) -> Vec<Result<String, String>> {
+    let mut acc = vec![];
+
+    // handle prebindings
+    for statement in ast.0.iter() {
+      self.prebinding(statement);
+    }
+
+    for statement in ast.0 {
+      match self.statement(statement) {
+        Ok(Some(ref output)) if repl => {
+          acc.push(Ok(output.to_repl()))
+        },
+        Ok(_) => (),
+        Err(error) => {
+          acc.push(Err(format!("Runtime error: {}", error)));
+          return acc;
+        },
+      }
+    }
+    acc
+  }
+
+  fn prebinding(&mut self, stmt: &Stmt) {
+    match stmt {
+      Stmt::PreBinding { name, func } => {
+        let v_entry = ValueEntry::Binding { constant: true, val: Node::Expr(Expr::Func(func.clone())) };
+        self.values.insert(name.clone(), v_entry);
+      },
+      Stmt::Expr(_expr) => {
+        //TODO have this support things like nested function defs
+
+      },
+      _ => ()
+    }
+  }
+
+  fn statement(&mut self, stmt: Stmt) -> EvalResult<Option<Node>> {
+    match stmt {
+      Stmt::Binding { name, constant, expr } => {
+        let val = self.expression(Node::Expr(expr))?;
+        self.values.insert(name.clone(), ValueEntry::Binding { constant, val });
+        Ok(None)
+      },
+      Stmt::Expr(expr) => Ok(Some(self.expression(expr.to_node())?)),
+      Stmt::PreBinding {..} | Stmt::Noop => Ok(None),
+    }
+  }
+
+  fn block(&mut self, stmts: Vec<Stmt>) -> EvalResult<Node> {
+    let mut ret = None;
+    for stmt in stmts {
+      ret = self.statement(stmt)?;
+    }
+    Ok(ret.unwrap_or(Node::Expr(Expr::Unit)))
+  }
+
+  fn expression(&mut self, node: Node) -> EvalResult<Node> {
+    use self::Expr::*;
+    match node {
+      t @ Node::PrimTuple { .. } => Ok(t),
+      obj @ Node::PrimObject { .. } =>  Ok(obj),
+      Node::Expr(expr) => match expr {
+        literal @ Lit(_) => Ok(Node::Expr(literal)),
+        Call { box f, args } => self.call_expression(f, args),
+        Sym(name) => Ok(match self.values.lookup(&name) {
+          Some(ValueEntry::Binding { val, .. }) => val.clone(),
+          None => return Err(format!("Could not look up symbol {}", name))
+        }),
+        Constructor { arity, ref name, tag, .. } if arity == 0 => Ok(Node::PrimObject { name: name.clone(), tag, items: vec![] }),
+        constructor @ Constructor { .. } => Ok(Node::Expr(constructor)),
+        func @ Func(_) => Ok(Node::Expr(func)),
+        Tuple(exprs) => {
+          let nodes = exprs.into_iter().map(|expr| self.expression(Node::Expr(expr))).collect::<Result<Vec<Node>,_>>()?;
+          Ok(Node::PrimTuple { items: nodes })
+        },
+        Conditional { box cond, then_clause, else_clause } => self.conditional(cond, then_clause, else_clause),
+        Assign { box val, box expr } => self.assign_expression(val, expr),
+        Unit => Ok(Node::Expr(Unit)),
+        CaseMatch { box cond, alternatives } => self.case_match_expression(cond, alternatives),
+        ConditionalTargetSigilValue => Ok(Node::Expr(ConditionalTargetSigilValue)),
+        UnimplementedSigilValue => Err(format!("Sigil value eval not implemented")),
+        ReductionError(err) => Err(format!("Reduction error: {}", err)),
+      }
+    }
+  }
+
+  fn call_expression(&mut self, f: Expr, args: Vec<Expr>) -> EvalResult<Node> {
+    use self::Expr::*;
+    match self.expression(Node::Expr(f))? {
+      Node::Expr(Constructor { type_name, name, tag, arity }) => self.apply_data_constructor(type_name, name, tag, arity, args),
+      Node::Expr(Func(f)) => self.apply_function(f, args),
+      other => return Err(format!("Tried to call {:?} which is not a function or data constructor", other)),
+    }
+  }
+
+  fn apply_data_constructor(&mut self, _type_name: Rc<String>, name: Rc<String>, tag: usize, arity: usize, args: Vec<Expr>) -> EvalResult<Node> {
+    if arity != args.len() {
+      return Err(format!("Data constructor {} requires {} arg(s)", name, arity));
+    }
+
+    let evaled_args = args.into_iter().map(|expr| self.expression(Node::Expr(expr))).collect::<Result<Vec<Node>,_>>()?;
+    //let evaled_args = vec![];
+    Ok(Node::PrimObject {
+      name: name.clone(),
+      items: evaled_args,
+      tag 
+    })
+  }
+
+  fn apply_function(&mut self, f: Func, args: Vec<Expr>) -> EvalResult<Node> {
+    match f {
+      Func::BuiltIn(builtin) => Ok(self.apply_builtin(builtin, args)?),
+      Func::UserDefined { params, body, name } => {
+
+        if params.len() != args.len() {
+          return Err(format!("calling a {}-argument function with {} args", params.len(), args.len()))
+        }
+        let mut func_state = State {
+          values: self.values.new_scope(name.map(|n| format!("{}", n))),
+        };
+        for (param, val) in params.into_iter().zip(args.into_iter()) {
+          let val = func_state.expression(Node::Expr(val))?;
+          func_state.values.insert(param, ValueEntry::Binding { constant: true, val });
+        }
+        // TODO figure out function return semantics
+        func_state.block(body)
+      }
+    }
+  }
+
+  fn apply_builtin(&mut self, builtin: Builtin, args: Vec<Expr>) -> EvalResult<Node> {
+    use self::Expr::*;
+    use self::Lit::*;
+    use Builtin::*;
+
+    let evaled_args: Result<Vec<Node>, String> = args.into_iter().map(|arg| self.expression(arg.to_node()))
+      .collect();
+    let evaled_args = evaled_args?;
+
+    Ok(match (builtin, evaled_args.as_slice()) {
+      (FieldAccess, &[Node::PrimObject { .. }]) => {
+        //TODO implement field access
+        unimplemented!()
+      },
+      (binop, &[Node::Expr(ref lhs), Node::Expr(ref rhs)]) => match (binop, lhs, rhs) {
+        /* binops */
+        (Add, Lit(Nat(l)), Lit(Nat(r))) => Lit(Nat(l + r)),
+        (Concatenate, Lit(StringLit(ref s1)), Lit(StringLit(ref s2))) => Lit(StringLit(Rc::new(format!("{}{}", s1, s2)))),
+        (Subtract, Lit(Nat(l)), Lit(Nat(r))) => Lit(Nat(l - r)),
+        (Multiply, Lit(Nat(l)), Lit(Nat(r))) => Lit(Nat(l * r)),
+        (Divide, Lit(Nat(l)), Lit(Nat(r))) => Lit(Float((*l as f64)/ (*r as f64))),
+        (Quotient, Lit(Nat(l)), Lit(Nat(r))) => if *r == 0 {
+          return Err(format!("divide by zero"));
+        } else {
+          Lit(Nat(l / r))
+        },
+        (Modulo, Lit(Nat(l)), Lit(Nat(r))) => Lit(Nat(l % r)),
+        (Exponentiation, Lit(Nat(l)), Lit(Nat(r))) => Lit(Nat(l ^ r)),
+        (BitwiseAnd, Lit(Nat(l)), Lit(Nat(r))) => Lit(Nat(l & r)),
+        (BitwiseOr, Lit(Nat(l)), Lit(Nat(r))) => Lit(Nat(l | r)),
+
+        /* comparisons */
+        (Equality, Lit(Nat(l)), Lit(Nat(r))) => Lit(Bool(l == r)),
+        (Equality, Lit(Int(l)), Lit(Int(r))) => Lit(Bool(l == r)),
+        (Equality, Lit(Float(l)), Lit(Float(r))) => Lit(Bool(l == r)),
+        (Equality, Lit(Bool(l)), Lit(Bool(r))) => Lit(Bool(l == r)),
+        (Equality, Lit(StringLit(ref l)), Lit(StringLit(ref r))) => Lit(Bool(l == r)),
+
+        (LessThan, Lit(Nat(l)), Lit(Nat(r))) => Lit(Bool(l < r)),
+        (LessThan, Lit(Int(l)), Lit(Int(r))) => Lit(Bool(l < r)),
+        (LessThan, Lit(Float(l)), Lit(Float(r))) => Lit(Bool(l < r)),
+
+        (LessThanOrEqual, Lit(Nat(l)), Lit(Nat(r))) => Lit(Bool(l <= r)),
+        (LessThanOrEqual, Lit(Int(l)), Lit(Int(r))) => Lit(Bool(l <= r)),
+        (LessThanOrEqual, Lit(Float(l)), Lit(Float(r))) => Lit(Bool(l <= r)),
+
+        (GreaterThan, Lit(Nat(l)), Lit(Nat(r))) => Lit(Bool(l > r)),
+        (GreaterThan, Lit(Int(l)), Lit(Int(r))) => Lit(Bool(l > r)),
+        (GreaterThan, Lit(Float(l)), Lit(Float(r))) => Lit(Bool(l > r)),
+
+        (GreaterThanOrEqual, Lit(Nat(l)), Lit(Nat(r))) => Lit(Bool(l >= r)),
+        (GreaterThanOrEqual, Lit(Int(l)), Lit(Int(r))) => Lit(Bool(l >= r)),
+        (GreaterThanOrEqual, Lit(Float(l)), Lit(Float(r))) => Lit(Bool(l >= r)),
+        _ => return Err("No valid binop".to_string())
+      }.to_node(),
+      (prefix, &[Node::Expr(ref arg)]) => match (prefix, arg) {
+        (BooleanNot, Lit(Bool(true))) => Lit(Bool(false)),
+        (BooleanNot, Lit(Bool(false))) => Lit(Bool(true)),
+        (Negate, Lit(Nat(n))) => Lit(Int(-1*(*n as i64))),
+        (Negate, Lit(Int(n))) => Lit(Int(-1*(*n as i64))),
+        (Increment, Lit(Int(n))) => Lit(Int(*n)),
+        (Increment, Lit(Nat(n))) => Lit(Nat(*n)),
+        _ => return Err("No valid prefix op".to_string())
+      }.to_node(),
+
+      /* builtin functions */
+      (IOPrint, &[ref anything]) => {
+        print!("{}", anything.to_repl());
+        Expr::Unit.to_node()
+      },
+      (IOPrintLn, &[ref anything]) => {
+        println!("{}", anything.to_repl());
+        Expr::Unit.to_node()
+      },
+      (IOGetLine, &[]) => {
+        let mut buf = String::new();
+        io::stdin().read_line(&mut buf).expect("Error readling line in 'getline'");
+        Lit(StringLit(Rc::new(buf.trim().to_string()))).to_node()
+      },
+      (x, args) => return Err(format!("bad or unimplemented builtin {:?} | {:?}", x, args)),
+    })
+  }
+
+  fn conditional(&mut self, cond: Expr, then_clause: Vec<Stmt>, else_clause: Vec<Stmt>) -> EvalResult<Node> {
+    let cond = self.expression(Node::Expr(cond))?;
+    Ok(match cond {
+      Node::Expr(Expr::Lit(Lit::Bool(true))) =>  self.block(then_clause)?,
+      Node::Expr(Expr::Lit(Lit::Bool(false))) => self.block(else_clause)?,
+      _ => return Err(format!("Conditional with non-boolean condition"))
+    })
+  }
+
+  fn assign_expression(&mut self, val: Expr, expr: Expr) -> EvalResult<Node> {
+    let name = match val  {
+      Expr::Sym(name) => name,
+      _ => return Err(format!("Trying to assign to a non-value")),
+    };
+
+    let constant = match self.values.lookup(&name) {
+      None => return Err(format!("Constant {} is undefined", name)),
+      Some(ValueEntry::Binding { constant, .. }) => constant.clone(),
+    };
+    if constant {
+      return Err(format!("trying to update {}, a non-mutable binding", name));
+    }
+    let val = self.expression(Node::Expr(expr))?;
+    self.values.insert(name.clone(), ValueEntry::Binding { constant: false, val });
+    Ok(Node::Expr(Expr::Unit))
+  }
+
+  fn guard_passes(&mut self, guard: &Option<Expr>, cond: &Node) -> EvalResult<bool> {
+    if let Some(ref guard_expr) = guard {
+      let guard_expr = match cond {
+        Node::Expr(ref e) => guard_expr.clone().replace_conditional_target_sigil(e),
+        _ => guard_expr.clone()
+      };
+      Ok(self.expression(guard_expr.to_node())?.is_true())
+    } else {
+      Ok(true)
+    }
+  }
+
+  fn case_match_expression(&mut self, cond: Expr, alternatives: Vec<Alternative>) -> EvalResult<Node> {
+
+    //TODO need to handle recursive subpatterns
+    let all_subpatterns_pass = |state: &mut State, subpatterns: &Vec<Option<Subpattern>>, items: &Vec<Node>| -> EvalResult<bool> {
+
+      if subpatterns.len() == 0 {
+        return Ok(true)
+      }
+
+      if items.len() != subpatterns.len() {
+        return Err(format!("Subpattern length isn't correct items {} subpatterns {}", items.len(), subpatterns.len()));
+      }
+
+      for (maybe_subp, cond) in subpatterns.iter().zip(items.iter()) {
+        if let Some(subp) = maybe_subp {
+          if !state.guard_passes(&subp.guard, &cond)? {
+            return Ok(false)
+          }
+        }
+      }
+      Ok(true)
+    };
+
+    let cond = self.expression(Node::Expr(cond))?;
+    for alt in alternatives {
+      // no matter what type of condition we have, ignore alternative if the guard evaluates false
+      if !self.guard_passes(&alt.matchable.guard, &cond)? {
+        continue;
+      }
+
+      match cond {
+        Node::PrimObject { ref tag, ref items, .. } => {
+          if alt.matchable.tag.map(|t| t == *tag).unwrap_or(true) {
+            let mut inner_state = self.new_frame(items, &alt.matchable.bound_vars);
+            if all_subpatterns_pass(&mut inner_state, &alt.matchable.subpatterns, items)? {
+              return inner_state.block(alt.item);
+            } else {
+              continue;
+            }
+          }
+        },
+        Node::PrimTuple { ref items } =>  {
+          let mut inner_state = self.new_frame(items, &alt.matchable.bound_vars);
+          if all_subpatterns_pass(&mut inner_state, &alt.matchable.subpatterns, items)? {
+            return inner_state.block(alt.item);
+          } else {
+            continue;
+          }
+        },
+        Node::Expr(ref _e) => {
+          if let None = alt.matchable.tag {
+            return self.block(alt.item)
+          }
+        }
+      }
+    }
+    Err(format!("{:?} failed pattern match", cond))
+  }
+}
--- a/schala-lang/language/src/eval/test.rs
+++ b/schala-lang/language/src/eval/test.rs
@ -0,0 +1,269 @@
+#![cfg(test)]
+
+use std::cell::RefCell;
+use std::rc::Rc;
+
+use crate::symbol_table::SymbolTable;
+use crate::scope_resolution::ScopeResolver;
+use crate::reduced_ast::reduce;
+use crate::eval::State;
+
+fn evaluate_all_outputs(input: &str) -> Vec<Result<String, String>> {
+  let (mut ast, source_map) = crate::util::quick_ast(input);
+  let source_map = Rc::new(RefCell::new(source_map));
+  let symbol_table = Rc::new(RefCell::new(SymbolTable::new(source_map)));
+  symbol_table.borrow_mut().add_top_level_symbols(&ast).unwrap();
+  {
+  let mut scope_resolver = ScopeResolver::new(symbol_table.clone());
+  let _ = scope_resolver.resolve(&mut ast);
+  }
+
+  let reduced = reduce(&ast, &symbol_table.borrow());
+  let mut state = State::new();
+  let all_output = state.evaluate(reduced, true);
+  all_output
+}
+
+macro_rules! test_in_fresh_env {
+  ($string:expr, $correct:expr) => {
+    {
+      let all_output = evaluate_all_outputs($string);
+      let ref output = all_output.last().unwrap();
+      assert_eq!(**output, Ok($correct.to_string()));
+    }
+  }
+}
+
+#[test]
+fn test_basic_eval() {
+  test_in_fresh_env!("1 + 2", "3");
+  test_in_fresh_env!("let mut a = 1; a = 2", "Unit");
+  /*
+     test_in_fresh_env!("let mut a = 1; a = 2; a", "2");
+     test_in_fresh_env!(r#"("a", 1 + 2)"#, r#"("a", 3)"#);
+     */
+}
+
+#[test]
+fn op_eval() {
+  test_in_fresh_env!("- 13", "-13");
+  test_in_fresh_env!("10 - 2", "8");
+}
+
+#[test]
+fn function_eval() {
+  test_in_fresh_env!("fn oi(x) { x + 1 }; oi(4)", "5");
+  test_in_fresh_env!("fn oi(x) { x + 1 }; oi(1+2)", "4");
+}
+
+#[test]
+fn scopes() {
+  let scope_ok = r#"
+    let a = 20
+    fn haha() {
+      let a = 10
+      a
+    }
+    haha()
+    "#;
+    test_in_fresh_env!(scope_ok, "10");
+    let scope_ok = r#"
+    let a = 20
+    fn queque() {
+      let a = 10
+      a
+    }
+    a
+    "#;
+    test_in_fresh_env!(scope_ok, "20");
+}
+
+#[test]
+fn if_is_patterns() {
+  let source = r#"
+type Option<T> = Some(T) | None
+let x = Option::Some(9); if x is Option::Some(q) then { q } else { 0 }"#;
+  test_in_fresh_env!(source, "9");
+
+  let source = r#"
+type Option<T> = Some(T) | None
+let x = Option::None; if x is Option::Some(q) then { q } else { 0 }"#;
+  test_in_fresh_env!(source, "0");
+}
+
+#[test]
+fn full_if_matching() {
+  let source = r#"
+type Option<T> = Some(T) | None
+let a = Option::None
+if a { is Option::None then 4, is Option::Some(x) then x }
+"#;
+test_in_fresh_env!(source, "4");
+
+let source = r#"
+type Option<T> = Some(T) | None
+let a = Option::Some(99)
+if a { is Option::None then 4, is Option::Some(x) then x }
+"#;
+test_in_fresh_env!(source, "99");
+
+let source = r#"
+let a = 10
+if a { is 10 then "x", is 4 then "y" }
+"#;
+test_in_fresh_env!(source, "\"x\"");
+
+let source = r#"
+let a = 10
+if a { is 15 then "x", is 10 then "y" }
+"#;
+test_in_fresh_env!(source, "\"y\"");
+}
+
+#[test]
+fn string_pattern() {
+  let source = r#"
+let a = "foo"
+if a { is "foo" then "x", is _ then "y" }
+"#;
+test_in_fresh_env!(source, "\"x\"");
+}
+
+#[test]
+fn boolean_pattern() {
+  let source = r#"
+let a = true
+if a {
+  is true then "x",
+  is false then "y"
+}
+"#;
+test_in_fresh_env!(source, "\"x\"");
+}
+
+#[test]
+fn boolean_pattern_2() {
+  let source = r#"
+let a = false
+if a { is true then "x", is false then "y" }
+"#;
+test_in_fresh_env!(source, "\"y\"");
+}
+
+#[test]
+fn ignore_pattern() {
+  let source = r#"
+type Option<T> = Some(T) | None
+if Option::Some(10) {
+  is _ then "hella"
+}
+"#;
+test_in_fresh_env!(source, "\"hella\"");
+}
+
+#[test]
+fn tuple_pattern() {
+  let source = r#"
+if (1, 2) {
+  is (1, x) then x,
+  is _ then 99
+}
+"#;
+test_in_fresh_env!(source, 2);
+}
+
+
+#[test]
+fn tuple_pattern_2() {
+  let source = r#"
+if (1, 2) {
+  is (10, x) then x,
+  is (y, x) then x + y
+}
+"#;
+test_in_fresh_env!(source, 3);
+}
+
+#[test]
+fn tuple_pattern_3() {
+  let source = r#"
+if (1, 5) {
+  is (10, x) then x,
+  is (1, x) then x
+}
+"#;
+test_in_fresh_env!(source, 5);
+}
+
+#[test]
+fn tuple_pattern_4() {
+  let source = r#"
+if (1, 5) {
+  is (10, x) then x,
+  is (1, x) then x,
+}
+"#;
+test_in_fresh_env!(source, 5);
+}
+
+#[test]
+fn  prim_obj_pattern() {
+  let source = r#"
+type Stuff = Mulch(Nat) | Jugs(Nat, String) | Mardok
+let a = Stuff::Mulch(20)
+let b = Stuff::Jugs(1, "haha")
+let c = Stuff::Mardok
+
+let x = if a {
+  is Stuff::Mulch(20) then "x",
+  is _ then "ERR"
+}
+
+let y = if b {
+  is Stuff::Mulch(n) then "ERR",
+  is Stuff::Jugs(2, _) then "ERR",
+  is Stuff::Jugs(1, s) then s,
+  is _ then "ERR",
+}
+
+let z = if c {
+  is Stuff::Jugs(_, _) then "ERR",
+  is Stuff::Mardok then "NIGH",
+  is _ then "ERR",
+}
+
+(x, y, z)
+"#;
+test_in_fresh_env!(source, r#"("x", "haha", "NIGH")"#);
+}
+
+#[test]
+fn basic_lambda_syntax() {
+  let source = r#"
+let q = \(x, y) { x * y }
+let x = q(5,2)
+let y = \(m, n, o) { m + n + o }(1,2,3)
+(x, y)
+  "#;
+test_in_fresh_env!(source, r"(10, 6)");
+}
+
+#[test]
+fn lambda_syntax_2() {
+  let source = r#"
+fn milta() {
+  \(x) { x + 33 }
+}
+milta()(10)
+  "#;
+  test_in_fresh_env!(source, "43");
+  }
+
+#[test]
+fn import_all() {
+  let source = r#"
+type Option<T> = Some(T) | None
+import Option::*
+let x = Some(9); if x is Some(q) then { q } else { 0 }"#;
+  test_in_fresh_env!(source, "9");
+}
--- a/schala-lang/language/src/lib.rs
+++ b/schala-lang/language/src/lib.rs
@ -1,31 +1,46 @@
 #![feature(trace_macros)]
 //#![feature(unrestricted_attribute_tokens)]
-#![feature(box_patterns, iter_intersperse)]
+#![feature(slice_patterns, box_patterns, box_syntax)]

-//! `schala-lang` is where the Schala programming language is actually implemented.
+//! `schala-lang` is where the Schala programming language is actually implemented. 
 //! It defines the `Schala` type, which contains the state for a Schala REPL, and implements
 //! `ProgrammingLanguageInterface` and the chain of compiler passes for it.

-extern crate derivative;
+extern crate itertools;
+#[macro_use]
+extern crate lazy_static;
+#[macro_use]
+extern crate maplit;
 extern crate schala_repl;
+#[macro_use]
+extern crate schala_lang_codegen;
+extern crate ena;
+extern crate derivative;
+extern crate colored;
+extern crate radix_trie;
+
+
+macro_rules! bx {
+  ($e:expr) => { Box::new($e) }
+}

 #[macro_use]
 mod util;
-
 #[macro_use]
-mod type_inference;
+mod typechecking;
+mod debugging;

+mod tokenizing;
 mod ast;
 mod parsing;
 #[macro_use]
 mod symbol_table;
+mod scope_resolution;
 mod builtin;
-mod error;
-mod reduced_ir;
-mod tree_walk_eval;
-#[macro_use]
-mod identifier;
+mod reduced_ast;
+mod eval;
+mod source_map;

 mod schala;

-pub use schala::{Schala, SchalaConfig};
+pub use schala::Schala;
--- a/schala-lang/language/src/parsing.rs
+++ b/schala-lang/language/src/parsing.rs
--- a/schala-lang/language/src/parsing/test.rs
+++ b/schala-lang/language/src/parsing/test.rs
@ -0,0 +1,828 @@
+#![cfg(test)]
+use std::cell::RefCell;
+use std::rc::Rc;
+use std::str::FromStr;
+
+use super::{Parser, ParseResult, tokenize};
+use crate::ast::*;
+use super::Declaration::*;
+use super::Signature;
+use super::TypeIdentifier::*;
+use super::TypeSingletonName;
+use super::ExpressionKind::*;
+use super::Variant::*;
+use super::ForBody::*;
+
+fn make_parser(input: &str) -> Parser {
+  let source_map = crate::source_map::SourceMap::new();
+  let source_map_handle = Rc::new(RefCell::new(source_map));
+  let tokens: Vec<crate::tokenizing::Token> = tokenize(input);
+  let mut parser = super::Parser::new(source_map_handle);
+  parser.add_new_tokens(tokens);
+  parser
+}
+
+fn parse(input: &str) -> ParseResult<AST> {
+  let mut parser = make_parser(input);
+  parser.parse()
+}
+
+macro_rules! parse_test {
+  ($string:expr, $correct:expr) => {
+    assert_eq!(parse($string).unwrap(), $correct)
+  };
+}
+macro_rules! parse_test_wrap_ast {
+  ($string:expr, $correct:expr) => { parse_test!($string, AST { id: ItemIdStore::new_id(), statements: vec![$correct] }) }
+}
+macro_rules! parse_error {
+  ($string:expr) => { assert!(parse($string).is_err()) }
+}
+macro_rules! qname {
+  (  $( $component:expr),* ) => {
+    {
+    let mut components = vec![];
+    $(
+      components.push(rc!($component));
+    )*
+    QualifiedName { components, id: ItemIdStore::new_id() }
+    }
+  };
+}
+macro_rules! val {
+  ($var:expr) => { Value(QualifiedName { components: vec![Rc::new($var.to_string())], id: ItemIdStore::new_id() }) };
+}
+macro_rules! ty {
+  ($name:expr) => { Singleton(tys!($name)) }
+}
+macro_rules! tys {
+  ($name:expr) => { TypeSingletonName { name: Rc::new($name.to_string()), params: vec![] } };
+}
+
+macro_rules! decl {
+  ($expr_type:expr) => {
+    Statement { id: ItemIdStore::new_id(), kind: StatementKind::Declaration($expr_type) }
+  };
+}
+
+macro_rules! import {
+  ($import_spec:expr) => {
+    Statement { id: ItemIdStore::new_id(), kind: StatementKind::Import($import_spec) }
+  }
+}
+
+macro_rules! module {
+  ($module_spec:expr) => {
+    Statement { id: ItemIdStore::new_id(), kind: StatementKind::Module($module_spec) }
+  }
+}
+
+macro_rules! ex {
+  ($expr_type:expr) => { Expression::new(ItemIdStore::new_id(), $expr_type) };
+  ($expr_type:expr, $type_anno:expr) => { Expression::with_anno(ItemIdStore::new_id(), $expr_type, $type_anno) };
+  (s $expr_text:expr) => {
+    {
+      let mut parser = make_parser($expr_text);
+      parser.expression().unwrap()
+    }
+  };
+}
+
+macro_rules! inv {
+  ($expr_type:expr) => { InvocationArgument::Positional($expr_type) }
+}
+
+macro_rules! binexp {
+  ($op:expr, $lhs:expr, $rhs:expr) => { BinExp(BinOp::from_sigil($op), bx!(Expression::new(ItemIdStore::new_id(), $lhs).into()), bx!(Expression::new(ItemIdStore::new_id(), $rhs).into())) }
+}
+macro_rules! prefexp {
+  ($op:expr, $lhs:expr) => { PrefixExp(PrefixOp::from_str($op).unwrap(), bx!(Expression::new(ItemIdStore::new_id(), $lhs).into())) }
+}
+macro_rules! exst {
+  ($expr_type:expr) => { Statement { id: ItemIdStore::new_id(), kind: StatementKind::Expression(Expression::new(ItemIdStore::new_id(), $expr_type).into())} };
+  ($expr_type:expr, $type_anno:expr) => { Statement { id: ItemIdStore::new_id(), kind: StatementKind::Expression(Expression::with_anno(ItemIdStore::new_id(), $expr_type, $type_anno).into())} };
+  ($op:expr, $lhs:expr, $rhs:expr) => { Statement { id: ItemIdStore::new_id(), ,kind: StatementKind::Expression(ex!(binexp!($op, $lhs, $rhs)))}
+  };
+  (s $statement_text:expr) => {
+    {
+      let mut parser = make_parser($statement_text);
+      parser.statement().unwrap()
+    }
+  }
+}
+
+#[test]
+fn parsing_number_literals_and_binexps() {
+  parse_test_wrap_ast! { ".2", exst!(FloatLiteral(0.2)) };
+  parse_test_wrap_ast! { "8.1", exst!(FloatLiteral(8.1)) };
+
+  parse_test_wrap_ast! { "0b010", exst!(NatLiteral(2)) };
+  parse_test_wrap_ast! { "0b0_1_0_", exst!(NatLiteral(2)) }
+
+  parse_test_wrap_ast! {"0xff", exst!(NatLiteral(255)) };
+  parse_test_wrap_ast! {"0xf_f_", exst!(NatLiteral(255)) };
+
+  parse_test_wrap_ast! {"0xf_f_+1", exst!(binexp!("+", NatLiteral(255), NatLiteral(1))) };
+
+  parse_test! {"3; 4; 4.3",
+    AST {
+      id: ItemIdStore::new_id(),
+      statements: vec![exst!(NatLiteral(3)), exst!(NatLiteral(4)),
+      exst!(FloatLiteral(4.3))]
+    }
+  };
+
+  parse_test_wrap_ast!("1 + 2 * 3",
+    exst!(binexp!("+", NatLiteral(1), binexp!("*", NatLiteral(2), NatLiteral(3))))
+  );
+
+  parse_test_wrap_ast!("1 * 2 + 3",
+    exst!(binexp!("+", binexp!("*", NatLiteral(1), NatLiteral(2)), NatLiteral(3)))
+    ) ;
+
+  parse_test_wrap_ast!("1 && 2", exst!(binexp!("&&", NatLiteral(1), NatLiteral(2))));
+
+  parse_test_wrap_ast!("1 + 2 * 3 + 4", exst!(
+    binexp!("+",
+      binexp!("+", NatLiteral(1), binexp!("*", NatLiteral(2), NatLiteral(3))),
+      NatLiteral(4))));
+
+  parse_test_wrap_ast!("(1 + 2) * 3",
+    exst!(binexp!("*", binexp!("+", NatLiteral(1), NatLiteral(2)), NatLiteral(3))));
+
+  parse_test_wrap_ast!(".1 + .2", exst!(binexp!("+", FloatLiteral(0.1), FloatLiteral(0.2))));
+  parse_test_wrap_ast!("1 / 2", exst!(binexp!("/", NatLiteral(1), NatLiteral(2))));
+}
+
+#[test]
+fn parsing_tuples() {
+  parse_test_wrap_ast!("()", exst!(TupleLiteral(vec![])));
+  parse_test_wrap_ast!("(\"hella\", 34)", exst!(
+    TupleLiteral(
+      vec![ex!(s r#""hella""#).into(), ex!(s "34").into()]
+    )
+  ));
+  parse_test_wrap_ast!("((1+2), \"slough\")", exst!(TupleLiteral(vec![
+    ex!(binexp!("+", NatLiteral(1), NatLiteral(2))).into(),
+    ex!(StringLiteral(rc!(slough))).into(),
+  ])))
+}
+
+#[test]
+fn parsing_identifiers() {
+  parse_test_wrap_ast!("a", exst!(val!("a")));
+  parse_test_wrap_ast!("some_value", exst!(val!("some_value")));
+  parse_test_wrap_ast!("a + b", exst!(binexp!("+", val!("a"), val!("b"))));
+  //parse_test!("a[b]", AST(vec![Expression(
+  //parse_test!("a[]", <- TODO THIS NEEDS TO FAIL
+  //parse_test("a()[b]()[d]")
+  //TODO fix this parsing stuff
+  /*
+  parse_test! { "perspicacity()[a]", AST(vec![
+    exst!(Index {
+      indexee: bx!(ex!(Call { f: bx!(ex!(val!("perspicacity"))), arguments: vec![] })),
+      indexers: vec![ex!(val!("a"))]
+    })
+  ])
+  }
+  */
+  parse_test_wrap_ast!("a[b,c]", exst!(Index { indexee: bx!(ex!(val!("a"))), indexers: vec![ex!(val!("b")), ex!(val!("c"))]} ));
+
+  parse_test_wrap_ast!("None", exst!(val!("None")));
+  parse_test_wrap_ast!("Pandas {  a: x + y }",
+    exst!(NamedStruct { name: qname!(Pandas), fields: vec![(rc!(a), ex!(binexp!("+", val!("x"), val!("y"))))]})
+  );
+  parse_test_wrap_ast! { "Pandas { a: n, b: q, }",
+    exst!(NamedStruct { name: qname!(Pandas), fields:
+    vec![(rc!(a), ex!(val!("n"))), (rc!(b), ex!(val!("q")))]
+    }
+    )
+  };
+}
+
+
+#[test]
+fn qualified_identifiers() {
+  parse_test_wrap_ast! {
+    "let q_q = Yolo::Swaggins",
+    decl!(Binding { name: rc!(q_q), constant: true, type_anno: None,
+    expr: Expression::new(ItemIdStore::new_id(), Value(qname!(Yolo, Swaggins))),
+    })
+  }
+
+  parse_test_wrap_ast! {
+    "thing::item::call()",
+    exst!(Call { f: bx![ex!(Value(qname!(thing, item, call)))], arguments: vec![] })
+  }
+}
+
+#[test]
+fn reserved_words() {
+  parse_error!("module::item::call()");
+}
+
+#[test]
+fn parsing_complicated_operators() {
+  parse_test_wrap_ast!("a <- b", exst!(binexp!("<-", val!("a"), val!("b"))));
+  parse_test_wrap_ast!("a || b", exst!(binexp!("||", val!("a"), val!("b"))));
+  parse_test_wrap_ast!("a<>b", exst!(binexp!("<>", val!("a"), val!("b"))));
+  parse_test_wrap_ast!("a.b.c.d", exst!(binexp!(".",
+                                              binexp!(".",
+                                                binexp!(".", val!("a"), val!("b")),
+                                              val!("c")),
+                                              val!("d"))));
+  parse_test_wrap_ast!("-3", exst!(prefexp!("-", NatLiteral(3))));
+  parse_test_wrap_ast!("-0.2", exst!(prefexp!("-", FloatLiteral(0.2))));
+  parse_test_wrap_ast!("!3", exst!(prefexp!("!", NatLiteral(3))));
+  parse_test_wrap_ast!("a <- -b", exst!(binexp!("<-", val!("a"), prefexp!("-", val!("b")))));
+  parse_test_wrap_ast!("a <--b", exst!(binexp!("<--", val!("a"), val!("b"))));
+}
+
+#[test]
+fn parsing_functions() {
+  parse_test_wrap_ast!("fn oi()",  decl!(FuncSig(Signature { name: rc!(oi), operator: false, params: vec![], type_anno: None })));
+  parse_test_wrap_ast!("oi()", exst!(Call { f: bx!(ex!(val!("oi"))), arguments: vec![] }));
+  parse_test_wrap_ast!("oi(a, 2 + 2)", exst!(Call
+  { f: bx!(ex!(val!("oi"))),
+    arguments: vec![inv!(ex!(val!("a"))), inv!(ex!(binexp!("+", NatLiteral(2), NatLiteral(2)))).into()]
+  }));
+  parse_error!("a(b,,c)");
+
+  parse_test_wrap_ast!("fn a(b, c: Int): Int", decl!(
+      FuncSig(Signature { name: rc!(a), operator: false, params: vec![
+        FormalParam { name: rc!(b), anno: None, default: None },
+        FormalParam { name: rc!(c), anno: Some(ty!("Int")), default: None }
+      ], type_anno: Some(ty!("Int")) })));
+
+
+  parse_test_wrap_ast!("fn a(x) { x() }", decl!(
+      FuncDecl(Signature { name: rc!(a), operator: false, params: vec![FormalParam { name: rc!(x), anno: None, default: None }], type_anno: None },
+      vec![exst!(Call { f: bx!(ex!(val!("x"))), arguments: vec![] })])));
+  parse_test_wrap_ast!("fn a(x) {\n x() }", decl!(
+      FuncDecl(Signature { name: rc!(a), operator: false, params: vec![FormalParam { name: rc!(x), anno: None, default: None }], type_anno: None },
+      vec![exst!(Call { f: bx!(ex!(val!("x"))), arguments: vec![] })])));
+
+  let multiline = r#"
+fn a(x) {
+x()
+}
+"#;
+parse_test_wrap_ast!(multiline, decl!(
+    FuncDecl(Signature { name: rc!(a), operator: false, params: vec![FormalParam { name: rc!(x), default: None, anno: None }], type_anno: None },
+    vec![exst!(Call { f: bx!(ex!(val!("x"))), arguments: vec![] })])));
+  let multiline2 = r#"
+fn a(x) {
+
+x()
+
+}
+"#;
+parse_test_wrap_ast!(multiline2, decl!(
+    FuncDecl(Signature { name: rc!(a), operator: false, params: vec![FormalParam { name: rc!(x), default: None, anno: None }], type_anno: None },
+    vec![exst!(s "x()")])));
+}
+
+#[test]
+fn functions_with_default_args() {
+  parse_test_wrap_ast! {
+    "fn func(x: Int, y: Int = 4) { }",
+    decl!(
+      FuncDecl(Signature { name: rc!(func), operator: false, type_anno: None, params: vec![
+        FormalParam { name: rc!(x), default: None, anno: Some(ty!("Int")) },
+        FormalParam { name: rc!(y), default: Some(ex!(s "4")), anno: Some(ty!("Int")) }
+      ]}, vec![])
+    )
+  };
+}
+
+#[test]
+fn parsing_bools() {
+  parse_test_wrap_ast!("false", exst!(BoolLiteral(false)));
+  parse_test_wrap_ast!("true", exst!(BoolLiteral(true)));
+}
+
+#[test]
+fn parsing_strings() {
+  parse_test_wrap_ast!(r#""hello""#, exst!(StringLiteral(rc!(hello))));
+}
+
+#[test]
+fn parsing_types() {
+  parse_test_wrap_ast!("type Yolo = Yolo", decl!(TypeDecl { name: tys!("Yolo"), body: TypeBody(vec![UnitStruct(rc!(Yolo))]), mutable: false} ));
+  parse_test_wrap_ast!("type mut Yolo = Yolo", decl!(TypeDecl { name: tys!("Yolo"), body: TypeBody(vec![UnitStruct(rc!(Yolo))]), mutable: true} ));
+  parse_test_wrap_ast!("type alias Sex = Drugs", decl!(TypeAlias { alias: rc!(Sex), original: rc!(Drugs) }));
+  parse_test_wrap_ast!("type Sanchez = Miguel | Alejandro(Int, Option<a>) | Esperanza { a: Int, b: String }",
+  decl!(TypeDecl {
+    name: tys!("Sanchez"),
+    body: TypeBody(vec![
+      UnitStruct(rc!(Miguel)),
+      TupleStruct(rc!(Alejandro), vec![
+        Singleton(TypeSingletonName { name: rc!(Int), params: vec![] }),
+        Singleton(TypeSingletonName { name: rc!(Option), params: vec![Singleton(TypeSingletonName { name: rc!(a), params: vec![] })] }),
+      ]),
+      Record{
+        name: rc!(Esperanza),
+        members: vec![
+          (rc!(a), Singleton(TypeSingletonName { name: rc!(Int), params: vec![] })),
+          (rc!(b), Singleton(TypeSingletonName { name: rc!(String), params: vec![] })),
+        ]
+      }
+    ]),
+    mutable: false
+  }));
+
+  parse_test_wrap_ast! {
+    "type Jorge<a> = Diego | Kike(a)",
+    decl!(TypeDecl{
+      name: TypeSingletonName { name: rc!(Jorge), params: vec![Singleton(TypeSingletonName { name: rc!(a), params: vec![] })] },
+      body: TypeBody(vec![UnitStruct(rc!(Diego)), TupleStruct(rc!(Kike), vec![Singleton(TypeSingletonName { name: rc!(a), params: vec![] })])]),
+      mutable: false
+    }
+    )
+  };
+}
+
+#[test]
+fn parsing_bindings() {
+  parse_test_wrap_ast!("let mut a = 10", decl!(Binding { name: rc!(a), constant: false, type_anno: None, expr: ex!(NatLiteral(10)) } ));
+  parse_test_wrap_ast!("let a = 2 + 2", decl!(Binding { name: rc!(a), constant: true, type_anno: None, expr: ex!(binexp!("+", NatLiteral(2), NatLiteral(2))) }));
+  parse_test_wrap_ast!("let a: Nat = 2 + 2", decl!(
+      Binding { name: rc!(a), constant: true, type_anno: Some(Singleton(TypeSingletonName { name: rc!(Nat), params: vec![] })),
+      expr: ex!(binexp!("+", NatLiteral(2), NatLiteral(2))) }
+  ));
+}
+
+#[test]
+fn parsing_block_expressions() {
+  parse_test_wrap_ast! {
+    "if a() then { b(); c() }", exst!(
+      IfExpression {
+        discriminator: Some(bx! {
+          ex!(Call { f: bx!(ex!(val!("a"))), arguments: vec![]})
+        }),
+        body: bx! {
+          IfExpressionBody::SimpleConditional {
+            then_case: vec![exst!(Call { f: bx!(ex!(val!("b"))), arguments: vec![]}), exst!(Call { f: bx!(ex!(val!("c"))), arguments: vec![] })],
+            else_case: None,
+          }
+        }
+      }
+    )
+  };
+
+  parse_test_wrap_ast! {
+    "if a() then { b(); c() } else { q }", exst!(
+      IfExpression {
+        discriminator: Some(bx! {
+          ex!(Call { f: bx!(ex!(val!("a"))), arguments: vec![]})
+        }),
+        body: bx! {
+          IfExpressionBody::SimpleConditional {
+            then_case: vec![exst!(Call { f: bx!(ex!(val!("b"))), arguments: vec![]}), exst!(Call { f: bx!(ex!(val!("c"))), arguments: vec![] })],
+            else_case: Some(vec![exst!(val!("q"))]),
+          }
+        }
+      }
+    )
+  };
+
+  /*
+  parse_test!("if a() then { b(); c() }", AST(vec![exst!(
+      IfExpression(bx!(ex!(Call { f: bx!(ex!(val!("a"))), arguments: vec![]})),
+        vec![exst!(Call { f: bx!(ex!(val!("b"))), arguments: vec![]}), exst!(Call { f: bx!(ex!(val!("c"))), arguments: vec![] })],
+        None)
+      )]));
+  parse_test!(r#"
+  if true then {
+    const a = 10
+    b
+  } else {
+    c
+  }"#,
+  AST(vec![exst!(IfExpression(bx!(ex!(BoolLiteral(true))),
+    vec![decl!(Binding { name: rc!(a), constant: true, expr: ex!(NatLiteral(10)) }),
+          exst!(val!(rc!(b)))],
+    Some(vec![exst!(val!(rc!(c)))])))])
+  );
+
+  parse_test!("if a { b } else { c }", AST(vec![exst!(
+        IfExpression(bx!(ex!(val!("a"))),
+          vec![exst!(val!("b"))],
+          Some(vec![exst!(val!("c"))])))]));
+
+  parse_test!("if (A {a: 1}) { b } else { c }", AST(vec![exst!(
+        IfExpression(bx!(ex!(NamedStruct { name: rc!(A), fields: vec![(rc!(a), ex!(NatLiteral(1)))]})),
+          vec![exst!(val!("b"))],
+          Some(vec![exst!(val!("c"))])))]));
+
+  parse_error!("if A {a: 1} { b } else { c }");
+  */
+}
+#[test]
+fn parsing_interfaces() {
+  parse_test_wrap_ast!("interface Unglueable { fn unglue(a: Glue); fn mar(): Glue }",
+  decl!(Interface {
+    name: rc!(Unglueable),
+    signatures: vec![
+      Signature {
+        name: rc!(unglue),
+        operator: false,
+        params: vec![
+          FormalParam { name: rc!(a), anno: Some(Singleton(TypeSingletonName { name: rc!(Glue), params: vec![] })), default: None }
+        ],
+        type_anno: None
+      },
+      Signature { name: rc!(mar), operator: false, params: vec![], type_anno: Some(Singleton(TypeSingletonName { name: rc!(Glue), params: vec![] })) },
+    ]
+  })
+  );
+}
+
+#[test]
+fn parsing_impls() {
+  parse_test_wrap_ast!("impl Heh { fn yolo(); fn swagg(); }",
+  decl!(Impl {
+    type_name: ty!("Heh"),
+    interface_name: None,
+    block: vec![
+      FuncSig(Signature { name: rc!(yolo), operator: false, params: vec![], type_anno: None }),
+      FuncSig(Signature { name: rc!(swagg), operator: false, params: vec![], type_anno: None })
+    ] }));
+
+  parse_test_wrap_ast!("impl Mondai for Lollerino { fn yolo(); fn swagg(); }",
+  decl!(Impl {
+    type_name: ty!("Lollerino"),
+    interface_name: Some(TypeSingletonName { name: rc!(Mondai), params: vec![] }),
+    block: vec![
+      FuncSig(Signature { name: rc!(yolo), operator: false, params: vec![], type_anno: None}),
+      FuncSig(Signature { name: rc!(swagg), operator: false, params: vec![], type_anno: None })
+    ] }));
+
+  parse_test_wrap_ast!("impl Hella<T> for (Alpha, Omega) { }",
+  decl!(Impl {
+    type_name: Tuple(vec![ty!("Alpha"), ty!("Omega")]),
+    interface_name: Some(TypeSingletonName { name: rc!(Hella), params: vec![ty!("T")] }),
+    block: vec![]
+  })
+  );
+
+  parse_test_wrap_ast!("impl Option<WTFMate> { fn oi() }",
+  decl!(Impl {
+    type_name: Singleton(TypeSingletonName { name: rc!(Option), params: vec![ty!("WTFMate")]}),
+    interface_name: None,
+    block: vec![
+      FuncSig(Signature { name: rc!(oi), operator: false, params: vec![], type_anno: None }),
+    ]
+  }));
+}
+
+#[test]
+fn parsing_type_annotations() {
+  parse_test_wrap_ast!("let a = b : Int",
+    decl!(Binding { name: rc!(a), constant: true, type_anno: None, expr:
+      ex!(val!("b"), ty!("Int")) }));
+
+  parse_test_wrap_ast!("a : Int",
+    exst!(val!("a"), ty!("Int"))
+  );
+
+  parse_test_wrap_ast!("a : Option<Int>",
+    exst!(val!("a"), Singleton(TypeSingletonName { name: rc!(Option), params: vec![ty!("Int")] }))
+  );
+
+  parse_test_wrap_ast!("a : KoreanBBQSpecifier<Kimchi, Option<Bulgogi> >",
+    exst!(val!("a"), Singleton(TypeSingletonName { name: rc!(KoreanBBQSpecifier), params: vec![
+      ty!("Kimchi"), Singleton(TypeSingletonName { name: rc!(Option), params: vec![ty!("Bulgogi")] })
+    ] }))
+  );
+
+  parse_test_wrap_ast!("a : (Int, Yolo<a>)",
+    exst!(val!("a"), Tuple(
+      vec![ty!("Int"), Singleton(TypeSingletonName {
+        name: rc!(Yolo), params: vec![ty!("a")]
+      })])));
+}
+
+#[test]
+fn parsing_lambdas() {
+  parse_test_wrap_ast! { r#"\(x) { x + 1}"#, exst!(
+      Lambda { params: vec![FormalParam { name: rc!(x), anno: None, default: None } ], type_anno: None, body: vec![exst!(s "x + 1")] }
+    )
+  }
+
+  parse_test_wrap_ast!(r#"\  (x: Int, y) { a;b;c;}"#,
+    exst!(Lambda {
+      params: vec![
+        FormalParam { name: rc!(x), anno: Some(ty!("Int")), default: None },
+        FormalParam { name: rc!(y), anno: None, default: None }
+      ],
+      type_anno: None,
+      body: vec![exst!(s "a"), exst!(s "b"), exst!(s "c")]
+    })
+  );
+
+  parse_test_wrap_ast! { r#"\(x){y}(1)"#,
+    exst!(Call { f: bx!(ex!(
+      Lambda {
+        params: vec![
+          FormalParam { name: rc!(x), anno: None, default: None }
+        ],
+        type_anno: None,
+        body: vec![exst!(s "y")] }
+      )),
+      arguments: vec![inv!(ex!(NatLiteral(1))).into()] })
+  };
+
+  parse_test_wrap_ast! {
+    r#"\(x: Int): String { "q" }"#,
+    exst!(Lambda {
+      params: vec![
+        FormalParam { name: rc!(x), anno: Some(ty!("Int")), default: None },
+      ],
+      type_anno: Some(ty!("String")),
+      body: vec![exst!(s r#""q""#)]
+    })
+  }
+}
+
+#[test]
+fn single_param_lambda() {
+  parse_test_wrap_ast! {
+    r"\x { x + 10 }",
+    exst!(Lambda {
+      params: vec![FormalParam { name: rc!(x), anno: None, default: None }],
+      type_anno: None,
+      body: vec![exst!(s r"x + 10")]
+    })
+  }
+
+  parse_test_wrap_ast! {
+    r"\x: Nat { x + 10 }",
+    exst!(Lambda {
+      params: vec![FormalParam { name: rc!(x), anno: Some(ty!("Nat")), default: None }],
+      type_anno: None,
+      body: vec![exst!(s r"x + 10")]
+    })
+  }
+}
+
+#[test]
+fn more_advanced_lambdas() {
+  parse_test! {
+    r#"fn wahoo() { let a = 10; \(x) { x + a } };
+    wahoo()(3) "#,
+    AST {
+      id: ItemIdStore::new_id(),
+      statements: vec![
+        exst!(s r"fn wahoo() { let a = 10; \(x) { x + a } }"),
+        exst! {
+        Call {
+          f: bx!(ex!(Call { f: bx!(ex!(val!("wahoo"))), arguments: vec![] })),
+          arguments: vec![inv!(ex!(NatLiteral(3))).into()],
+        }
+      }
+    ]
+  }
+  }
+}
+
+#[test]
+  fn list_literals() {
+    parse_test_wrap_ast! {
+      "[1,2]",
+        exst!(ListLiteral(vec![ex!(NatLiteral(1)), ex!(NatLiteral(2))]))
+    };
+  }
+
+#[test]
+fn while_expr() {
+  parse_test_wrap_ast! {
+    "while { }",
+    exst!(WhileExpression { condition: None, body: vec![] })
+  }
+
+  parse_test_wrap_ast! {
+    "while a == b { }",
+    exst!(WhileExpression { condition: Some(bx![ex![binexp!("==", val!("a"), val!("b"))]]), body: vec![] })
+  }
+}
+
+#[test]
+fn for_expr() {
+  parse_test_wrap_ast! {
+    "for { a <- maybeValue } return 1",
+    exst!(ForExpression {
+      enumerators: vec![Enumerator { id: rc!(a), generator: ex!(val!("maybeValue")) }],
+      body: bx!(MonadicReturn(ex!(s "1")))
+    })
+  }
+
+  parse_test_wrap_ast! {
+    "for n <- someRange { f(n); }",
+    exst!(ForExpression { enumerators: vec![Enumerator { id: rc!(n), generator: ex!(val!("someRange"))}],
+      body: bx!(ForBody::StatementBlock(vec![exst!(s "f(n)")]))
+    })
+  }
+}
+
+#[test]
+fn patterns() {
+  parse_test_wrap_ast! {
+    "if x is Some(a) then { 4 } else { 9 }", exst!(
+      IfExpression {
+        discriminator: Some(bx!(ex!(s "x"))),
+        body: bx!(IfExpressionBody::SimplePatternMatch {
+          pattern: Pattern::TupleStruct(qname!(Some), vec![Pattern::VarOrName(qname!(a))]),
+          then_case: vec![exst!(s "4")],
+          else_case: Some(vec![exst!(s "9")]) })
+        }
+      )
+  }
+
+  parse_test_wrap_ast! {
+    "if x is Some(a) then 4 else 9", exst!(
+      IfExpression {
+        discriminator: Some(bx!(ex!(s "x"))),
+        body: bx!(IfExpressionBody::SimplePatternMatch {
+            pattern: Pattern::TupleStruct(qname!(Some), vec![Pattern::VarOrName(qname!(a))]),
+            then_case: vec![exst!(s "4")],
+            else_case: Some(vec![exst!(s "9")]) }
+          )
+        }
+    )
+  }
+
+  parse_test_wrap_ast! {
+    "if x is Something { a, b: x } then { 4 } else { 9 }", exst!(
+      IfExpression {
+        discriminator: Some(bx!(ex!(s "x"))),
+        body: bx!(IfExpressionBody::SimplePatternMatch {
+          pattern: Pattern::Record(qname!(Something), vec![
+                (rc!(a),Pattern::Literal(PatternLiteral::StringPattern(rc!(a)))),
+                (rc!(b),Pattern::VarOrName(qname!(x)))
+            ]),
+          then_case: vec![exst!(s "4")],
+          else_case: Some(vec![exst!(s "9")])
+          }
+        )
+      }
+    )
+  }
+}
+
+#[test]
+fn pattern_literals() {
+  parse_test_wrap_ast! {
+    "if x is -1 then 1 else 2",
+    exst!(
+      IfExpression {
+        discriminator: Some(bx!(ex!(s "x"))),
+        body: bx!(IfExpressionBody::SimplePatternMatch {
+            pattern: Pattern::Literal(PatternLiteral::NumPattern { neg: true, num: NatLiteral(1) }),
+            then_case: vec![exst!(NatLiteral(1))],
+            else_case: Some(vec![exst!(NatLiteral(2))]),
+        })
+      }
+    )
+  }
+
+  parse_test_wrap_ast! {
+    "if x is 1 then 1 else 2",
+    exst!(
+      IfExpression {
+        discriminator: Some(bx!(ex!(s "x"))),
+        body: bx!(IfExpressionBody::SimplePatternMatch {
+          pattern: Pattern::Literal(PatternLiteral::NumPattern { neg: false, num: NatLiteral(1) }),
+          then_case: vec![exst!(s "1")],
+          else_case: Some(vec![exst!(s "2")]),
+        })
+      }
+    )
+  }
+
+  parse_test_wrap_ast! {
+    "if x is true then 1 else 2",
+    exst!(
+    IfExpression {
+        discriminator: Some(bx!(ex!(s "x"))),
+        body: bx!(
+            IfExpressionBody::SimplePatternMatch {
+              pattern: Pattern::Literal(PatternLiteral::BoolPattern(true)),
+              then_case: vec![exst!(NatLiteral(1))],
+              else_case: Some(vec![exst!(NatLiteral(2))]),
+          })
+      }
+    )
+  }
+
+  parse_test_wrap_ast! {
+    "if x is \"gnosticism\" then 1 else 2",
+      exst!(
+        IfExpression {
+          discriminator: Some(bx!(ex!(s "x"))),
+          body: bx!(IfExpressionBody::SimplePatternMatch {
+              pattern: Pattern::Literal(PatternLiteral::StringPattern(rc!(gnosticism))),
+              then_case: vec![exst!(s "1")],
+              else_case: Some(vec![exst!(s "2")]),
+          })
+        }
+      )
+  }
+}
+
+#[test]
+fn imports() {
+  parse_test_wrap_ast! {
+    "import harbinger::draughts::Norgleheim",
+    import!(ImportSpecifier { 
+      id: ItemIdStore::new_id(),
+      path_components: vec![rc!(harbinger), rc!(draughts), rc!(Norgleheim)],
+      imported_names: ImportedNames::LastOfPath
+    })
+  }
+}
+
+#[test]
+fn imports_2() {
+  parse_test_wrap_ast! {
+    "import harbinger::draughts::{Norgleheim, Xraksenlaigar}",
+    import!(ImportSpecifier { 
+      id: ItemIdStore::new_id(),
+      path_components: vec![rc!(harbinger), rc!(draughts)],
+      imported_names: ImportedNames::List(vec![
+        rc!(Norgleheim),
+        rc!(Xraksenlaigar)
+      ])
+    })
+  }
+}
+
+#[test]
+fn imports_3() {
+  parse_test_wrap_ast! {
+    "import bespouri::{}",
+    import!(ImportSpecifier { 
+      id: ItemIdStore::new_id(),
+      path_components: vec![rc!(bespouri)],
+      imported_names: ImportedNames::List(vec![])
+    })
+  }
+}
+
+
+#[test]
+fn imports_4() {
+  parse_test_wrap_ast! {
+    "import bespouri::*",
+    import!(ImportSpecifier {
+      id: ItemIdStore::new_id(),
+      path_components: vec![rc!(bespouri)],
+      imported_names: ImportedNames::All
+    })
+  }
+}
+
+
+#[test]
+fn if_expr() {
+  parse_test_wrap_ast! {
+    "if x { is 1 then 5, else 20 }",
+    exst! {
+      IfExpression {
+        discriminator: Some(bx!(ex!(s "x"))),
+        body: bx!(IfExpressionBody::CondList(
+          vec![
+            ConditionArm {
+              condition: Condition::Pattern(Pattern::Literal(PatternLiteral::NumPattern { neg: false, num: NatLiteral(1)})),
+              guard: None,
+              body: vec![exst!(s "5")],
+            },
+            ConditionArm {
+              condition: Condition::Else,
+              guard: None,
+              body: vec![exst!(s "20")],
+            },
+          ]
+        ))
+      }
+    }
+  }
+}
+
+#[test]
+fn modules() {
+  parse_test_wrap_ast! {
+r#"
+  module ephraim {
+    let a = 10
+    fn nah() { 33 }
+  }
+"#,
+module!(
+  ModuleSpecifier { name: rc!(ephraim), contents: vec![
+    decl!(Binding { name: rc!(a), constant: true, type_anno: None, expr: ex!(s "10") }),
+    decl!(FuncDecl(Signature { name: rc!(nah), operator: false, params: vec![], type_anno: None }, vec![exst!(NatLiteral(33))])),
+  ] }
+)
+  }
+}
--- a/schala-lang/language/src/prelude.schala
+++ b/schala-lang/language/src/prelude.schala
@ -3,19 +3,11 @@ let _SCHALA_VERSION = "0.1.0"
 type Option<T> = Some(T) | None
 type Ord = LT | EQ | GT

-@register_builtin(print)
-fn print(arg) { }
-
-@register_builtin(println)
-fn println(arg) { }
-
-@register_builtin(getline)
-fn getline(arg) { }

 fn map(input: Option<T>, func: Func): Option<T> {
  if input {
-    is Option::Some(x) then Option::Some(func(x))
-    is Option::None then Option::None
+    is Option::Some(x) then Option::Some(func(x)),
+    is Option::None then Option::None,
  }
 }

--- a/schala-lang/language/src/reduced_ast.rs
+++ b/schala-lang/language/src/reduced_ast.rs
@ -0,0 +1,544 @@
+//! # Reduced AST
+//! The reduced AST is a minimal AST designed to be built from the full AST after all possible
+//! static checks have been done. Consequently, the AST reduction phase does very little error
+//! checking itself - any errors should ideally be caught either by an earlier phase, or are
+//! runtime errors that the evaluator should handle. That said, becuase it does do table lookups
+//! that can in principle fail [especially at the moment with most static analysis not yet complete],
+//! there is an Expr variant `ReductionError` to handle these cases.
+//!
+//! A design decision to make - should the ReducedAST types contain all information about
+//! type/layout necessary for the evaluator to work? If so, then the evaluator should not
+//! have access to the symbol table at all and ReducedAST should carry that information. If not,
+//! then ReducedAST shouldn't be duplicating information that can be queried at runtime from the
+//! symbol table. But I think the former might make sense since ultimately the bytecode will be
+//! built from the ReducedAST.
+use std::rc::Rc;
+use std::str::FromStr;
+
+use crate::ast::*;
+use crate::symbol_table::{Symbol, SymbolSpec, SymbolTable, FullyQualifiedSymbolName};
+use crate::builtin::Builtin;
+use crate::util::deref_optional_box;
+
+#[derive(Debug)]
+pub struct ReducedAST(pub Vec<Stmt>);
+
+#[derive(Debug, Clone)]
+pub enum Stmt {
+  PreBinding {
+    name: Rc<String>,
+    func: Func,
+  },
+  Binding {
+    name: Rc<String>,
+    constant: bool,
+    expr: Expr,
+  },
+  Expr(Expr),
+  Noop,
+}
+
+#[derive(Debug, Clone)]
+pub enum Expr {
+  Unit,
+  Lit(Lit),
+  Sym(Rc<String>), //a Sym is anything that can be looked up by name at runtime - i.e. a function or variable address
+  Tuple(Vec<Expr>),
+  Func(Func),
+  Constructor {
+    type_name: Rc<String>,
+    name: Rc<String>,
+    tag: usize,
+    arity: usize, // n.b. arity here is always the value from the symbol table - if it doesn't match what it's being called with, that's an eval error, eval will handle it
+  },
+  Call {
+    f: Box<Expr>,
+    args: Vec<Expr>,
+  },
+  Assign {
+    val: Box<Expr>, //TODO this probably can't be a val
+    expr: Box<Expr>,
+  },
+  Conditional {
+    cond: Box<Expr>,
+    then_clause: Vec<Stmt>,
+    else_clause: Vec<Stmt>,
+  },
+  ConditionalTargetSigilValue,
+  CaseMatch {
+    cond: Box<Expr>,
+    alternatives: Vec<Alternative>
+  },
+  UnimplementedSigilValue,
+  ReductionError(String),
+}
+
+pub type BoundVars = Vec<Option<Rc<String>>>; //remember that order matters here
+
+#[derive(Debug, Clone)]
+pub struct Alternative {
+  pub matchable: Subpattern,
+  pub item: Vec<Stmt>,
+}
+
+#[derive(Debug, Clone)]
+pub struct Subpattern {
+  pub tag: Option<usize>,
+  pub subpatterns: Vec<Option<Subpattern>>,
+  pub bound_vars: BoundVars,
+  pub guard: Option<Expr>,
+}
+
+#[derive(Debug, Clone)]
+pub enum Lit {
+  Nat(u64),
+  Int(i64),
+  Float(f64),
+  Bool(bool),
+  StringLit(Rc<String>),
+}
+
+#[derive(Debug, Clone)]
+pub enum Func {
+  BuiltIn(Builtin),
+  UserDefined {
+    name: Option<Rc<String>>,
+    params: Vec<Rc<String>>,
+    body: Vec<Stmt>,
+  }
+}
+
+pub fn reduce(ast: &AST, symbol_table: &SymbolTable) -> ReducedAST {
+  let mut reducer = Reducer { symbol_table };
+  reducer.ast(ast)
+}
+
+struct Reducer<'a> {
+  symbol_table: &'a SymbolTable
+}
+
+impl<'a> Reducer<'a> {
+  fn ast(&mut self, ast: &AST) -> ReducedAST {
+    let mut output = vec![];
+    for statement in ast.statements.iter() {
+      output.push(self.statement(statement));
+    }
+    ReducedAST(output)
+  }
+
+  fn statement(&mut self, stmt: &Statement) -> Stmt {
+    match &stmt.kind {
+      StatementKind::Expression(expr) => Stmt::Expr(self.expression(&expr)),
+      StatementKind::Declaration(decl) => self.declaration(&decl),
+      StatementKind::Import(_) => Stmt::Noop,
+      StatementKind::Module(modspec) => {
+        for statement in modspec.contents.iter() {
+          self.statement(&statement);
+        }
+        Stmt::Noop
+      }
+    }
+  }
+
+  fn block(&mut self, block: &Block) -> Vec<Stmt> {
+    block.iter().map(|stmt| self.statement(stmt)).collect()
+  }
+
+  fn invocation_argument(&mut self, invoc: &InvocationArgument) -> Expr {
+    use crate::ast::InvocationArgument::*;
+    match invoc {
+      Positional(ex) => self.expression(ex),
+      Keyword { .. } => Expr::UnimplementedSigilValue,
+      Ignored => Expr::UnimplementedSigilValue,
+    }
+  }
+
+  fn expression(&mut self, expr: &Expression) -> Expr {
+    use crate::ast::ExpressionKind::*;
+    let symbol_table = self.symbol_table;
+    let ref input = expr.kind;
+    match input {
+      NatLiteral(n) => Expr::Lit(Lit::Nat(*n)),
+      FloatLiteral(f) => Expr::Lit(Lit::Float(*f)),
+      StringLiteral(s) => Expr::Lit(Lit::StringLit(s.clone())),
+      BoolLiteral(b) => Expr::Lit(Lit::Bool(*b)),
+      BinExp(binop, lhs, rhs) => self.binop(binop, lhs, rhs),
+      PrefixExp(op, arg) => self.prefix(op, arg),
+      Value(qualified_name) => self.value(qualified_name),
+      Call { f, arguments } =>  self.reduce_call_expression(f, arguments),
+      TupleLiteral(exprs) => Expr::Tuple(exprs.iter().map(|e| self.expression(e)).collect()),
+      IfExpression { discriminator, body } => self.reduce_if_expression(deref_optional_box(discriminator), body),
+      Lambda { params, body, .. } => self.reduce_lambda(params, body),
+      NamedStruct { name, fields } => self.reduce_named_struct(name, fields),
+      Index { .. } => Expr::UnimplementedSigilValue,
+      WhileExpression { .. } => Expr::UnimplementedSigilValue,
+      ForExpression { .. } => Expr::UnimplementedSigilValue,
+      ListLiteral { .. } => Expr::UnimplementedSigilValue,
+    }
+  }
+
+  fn value(&mut self, qualified_name: &QualifiedName) -> Expr {
+    let symbol_table = self.symbol_table;
+    let ref id = qualified_name.id;
+    let ref sym_name = match symbol_table.get_fqsn_from_id(id) {
+      Some(fqsn) => fqsn,
+      None => return Expr::ReductionError(format!("FQSN lookup for Value {:?} failed", qualified_name)),
+    };
+
+    //TODO this probably needs to change
+    let FullyQualifiedSymbolName(ref v) = sym_name;
+    let name = v.last().unwrap().name.clone();
+
+    let Symbol { local_name, spec, .. } = match symbol_table.lookup_by_fqsn(&sym_name) {
+      Some(s) => s,
+      //None => return Expr::ReductionError(format!("Symbol {:?} not found", sym_name)),
+      None => return Expr::Sym(name.clone())
+    };
+
+    match spec {
+      SymbolSpec::RecordConstructor { .. } => Expr::ReductionError(format!("AST reducer doesn't expect a RecordConstructor here")),
+      SymbolSpec::DataConstructor { index, type_args, type_name } => Expr::Constructor {
+        type_name: type_name.clone(),
+        name: name.clone(),
+        tag: index.clone(),
+        arity: type_args.len(),
+      },
+      SymbolSpec::Func(_) => Expr::Sym(local_name.clone()),
+      SymbolSpec::Binding => Expr::Sym(local_name.clone()), //TODO not sure if this is right, probably needs to eventually be fqsn
+      SymbolSpec::Type { .. } => Expr::ReductionError("AST reducer doesnt expect a type here".to_string())
+    }
+  }
+
+  fn reduce_lambda(&mut self, params: &Vec<FormalParam>, body: &Block) -> Expr {
+    Expr::Func(Func::UserDefined {
+      name: None,
+      params: params.iter().map(|param| param.name.clone()).collect(),
+      body: self.block(body),
+    })
+  }
+
+  fn reduce_named_struct(&mut self, name: &QualifiedName, fields: &Vec<(Rc<String>, Expression)>) -> Expr {
+    let symbol_table = self.symbol_table;
+    let ref sym_name = match symbol_table.get_fqsn_from_id(&name.id) {
+      Some(fqsn) => fqsn,
+      None => return Expr::ReductionError(format!("FQSN lookup for name {:?} failed", name)),
+    };
+
+    let FullyQualifiedSymbolName(ref v) = sym_name;
+    let ref name = v.last().unwrap().name;
+    let (type_name, index, members_from_table) = match symbol_table.lookup_by_fqsn(&sym_name) {
+      Some(Symbol { spec: SymbolSpec::RecordConstructor { members, type_name, index },  .. }) => (type_name.clone(), index, members),
+      _ => return Expr::ReductionError("Not a record constructor".to_string()),
+    };
+    let arity = members_from_table.len();
+
+    let mut args: Vec<(Rc<String>, Expr)> = fields.iter()
+      .map(|(name, expr)| (name.clone(), self.expression(expr)))
+      .collect();
+
+    args.as_mut_slice()
+      .sort_unstable_by(|(name1, _), (name2, _)| name1.cmp(name2)); //arbitrary - sorting by alphabetical order
+
+    let args = args.into_iter().map(|(_, expr)| expr).collect();
+
+    //TODO make sure this sorting actually works
+    let f = box Expr::Constructor { type_name, name: name.clone(), tag: *index, arity, };
+    Expr::Call { f, args }
+  }
+
+  fn reduce_call_expression(&mut self, func: &Expression, arguments: &Vec<InvocationArgument>) -> Expr {
+    Expr::Call {
+      f: Box::new(self.expression(func)),
+      args: arguments.iter().map(|arg| self.invocation_argument(arg)).collect(),
+    }
+  }
+
+  fn reduce_if_expression(&mut self, discriminator: Option<&Expression>, body: &IfExpressionBody) -> Expr {
+    let symbol_table = self.symbol_table;
+    let cond = Box::new(match discriminator {
+      Some(expr) => self.expression(expr),
+      None => return Expr::ReductionError(format!("blank cond if-expr not supported")),
+    });
+
+    match body {
+      IfExpressionBody::SimpleConditional { then_case, else_case } => {
+        let then_clause = self.block(&then_case);
+        let else_clause = match else_case.as_ref() {
+          None => vec![],
+          Some(stmts) => self.block(&stmts),
+        };
+        Expr::Conditional { cond, then_clause, else_clause }
+      },
+      IfExpressionBody::SimplePatternMatch { pattern, then_case, else_case } => {
+        let then_clause = self.block(&then_case);
+        let else_clause = match else_case.as_ref() {
+          None => vec![],
+          Some(stmts) => self.block(&stmts),
+        };
+
+        let alternatives = vec![
+          pattern.to_alternative(then_clause, symbol_table),
+          Alternative {
+            matchable: Subpattern {
+              tag: None,
+              subpatterns: vec![],
+              bound_vars: vec![],
+              guard: None,
+            },
+            item: else_clause
+          },
+        ];
+
+        Expr::CaseMatch {
+          cond,
+          alternatives,
+        }
+      },
+      IfExpressionBody::CondList(ref condition_arms) => {
+        let mut alternatives = vec![];
+        for arm in condition_arms {
+          match arm.condition {
+            Condition::Expression(ref _expr) => {
+              return Expr::UnimplementedSigilValue
+            },
+            Condition::Pattern(ref p) =>  {
+              let item = self.block(&arm.body);
+              let alt = p.to_alternative(item, symbol_table);
+              alternatives.push(alt);
+            },
+            Condition::TruncatedOp(_, _) => {
+              return Expr::UnimplementedSigilValue
+            },
+            Condition::Else => {
+              return Expr::UnimplementedSigilValue
+            }
+          }
+        }
+        Expr::CaseMatch { cond, alternatives }
+      }
+    }
+  }
+
+  fn binop(&mut self, binop: &BinOp, lhs: &Box<Expression>, rhs: &Box<Expression>) -> Expr {
+    let operation = Builtin::from_str(binop.sigil()).ok();
+    match operation {
+      Some(Builtin::Assignment) => Expr::Assign {
+        val: Box::new(self.expression(&*lhs)),
+        expr: Box::new(self.expression(&*rhs)),
+      },
+      Some(op) => {
+        let f = Box::new(Expr::Func(Func::BuiltIn(op)));
+        Expr::Call { f, args: vec![self.expression(&*lhs), self.expression(&*rhs)] }
+      },
+      None => {
+        //TODO handle a user-defined operation
+        Expr::UnimplementedSigilValue
+      }
+    }
+  }
+
+  fn prefix(&mut self, prefix: &PrefixOp, arg: &Box<Expression>) -> Expr {
+    match prefix.builtin {
+      Some(op) => {
+        let f = Box::new(Expr::Func(Func::BuiltIn(op)));
+        Expr::Call { f, args: vec![self.expression(arg)] }
+      },
+      None => { //TODO need this for custom prefix ops
+        Expr::UnimplementedSigilValue
+      }
+    }
+  }
+
+  fn declaration(&mut self, declaration: &Declaration) -> Stmt {
+    use self::Declaration::*;
+    match declaration {
+      Binding {name, constant, expr, .. } => Stmt::Binding { name: name.clone(), constant: *constant, expr: self.expression(expr) },
+      FuncDecl(Signature { name, params, .. }, statements) => Stmt::PreBinding {
+        name: name.clone(),
+        func: Func::UserDefined {
+          name: Some(name.clone()),
+          params: params.iter().map(|param| param.name.clone()).collect(),
+          body: self.block(&statements),
+        }
+      },
+      TypeDecl { .. } => Stmt::Noop,
+      TypeAlias{ .. } => Stmt::Noop,
+      Interface { .. } => Stmt::Noop,
+      Impl { .. } => Stmt::Expr(Expr::UnimplementedSigilValue),
+      _ => Stmt::Expr(Expr::UnimplementedSigilValue)
+    }
+  }
+}
+
+
+
+
+
+/*                     ig var   pat
+ * x is SomeBigOldEnum(_, x, Some(t))
+ */
+
+fn handle_symbol(symbol: Option<&Symbol>, inner_patterns: &Vec<Pattern>, symbol_table: &SymbolTable) -> Subpattern {
+  use self::Pattern::*;
+  let tag = symbol.map(|symbol| match symbol.spec {
+    SymbolSpec::DataConstructor { index, .. } => index.clone(),
+    _ => panic!("Symbol is not a data constructor - this should've been caught in type-checking"),
+  });
+  let bound_vars = inner_patterns.iter().map(|p| match p {
+    VarOrName(qualified_name) => {
+      let fqsn = symbol_table.get_fqsn_from_id(&qualified_name.id);
+      let symbol_exists = fqsn.and_then(|fqsn| symbol_table.lookup_by_fqsn(&fqsn)).is_some();
+      if symbol_exists {
+        None
+      } else {
+        let QualifiedName { components, .. } = qualified_name;
+        if components.len() == 1 {
+          Some(components[0].clone())
+        } else {
+          panic!("Bad variable name in pattern");
+        }
+      }
+    },
+    _ => None,
+  }).collect();
+
+  let subpatterns = inner_patterns.iter().map(|p| match p {
+    Ignored => None,
+    VarOrName(_) => None,
+    Literal(other) => Some(other.to_subpattern(symbol_table)),
+    tp @ TuplePattern(_) => Some(tp.to_subpattern(symbol_table)),
+    ts @ TupleStruct(_, _) => Some(ts.to_subpattern(symbol_table)),
+    Record(..) => unimplemented!(),
+  }).collect();
+
+  let guard = None;
+  /*
+     let guard_equality_exprs: Vec<Expr> = subpatterns.iter().map(|p| match p {
+     Literal(lit) => match lit {
+     _ => unimplemented!()
+     },
+     _ => unimplemented!()
+     }).collect();
+     */
+
+  Subpattern {
+    tag,
+    subpatterns,
+    guard,
+    bound_vars,
+  }
+}
+
+impl Pattern {
+  fn to_alternative(&self, item: Vec<Stmt>, symbol_table: &SymbolTable) -> Alternative {
+    let s = self.to_subpattern(symbol_table);
+    Alternative {
+      matchable: Subpattern {
+        tag: s.tag,
+        subpatterns: s.subpatterns,
+        bound_vars: s.bound_vars,
+        guard: s.guard,
+      },
+      item
+    }
+  }
+
+  fn to_subpattern(&self, symbol_table: &SymbolTable) -> Subpattern {
+    use self::Pattern::*;
+    match self {
+      TupleStruct(QualifiedName{ components, id }, inner_patterns) => {
+        let fqsn = symbol_table.get_fqsn_from_id(&id);
+        match fqsn.and_then(|fqsn| symbol_table.lookup_by_fqsn(&fqsn)) {
+          Some(symbol) => handle_symbol(Some(symbol), inner_patterns, symbol_table),
+          None => {
+            panic!("Symbol {:?} not found", components);
+          }
+        }
+      },
+      TuplePattern(inner_patterns) => handle_symbol(None, inner_patterns, symbol_table),
+      Record(_name, _pairs) => {
+        unimplemented!()
+      },
+      Ignored => Subpattern { tag: None, subpatterns: vec![], guard: None, bound_vars: vec![] },
+      Literal(lit) => lit.to_subpattern(symbol_table),
+      VarOrName(QualifiedName { components, id  }) => {
+        // if fqsn is Some, treat this as a symbol pattern. If it's None, treat it
+        // as a variable.
+        let fqsn = symbol_table.get_fqsn_from_id(&id);
+        match fqsn.and_then(|fqsn| symbol_table.lookup_by_fqsn(&fqsn)) {
+          Some(symbol) => handle_symbol(Some(symbol), &vec![], symbol_table),
+          None => {
+            let name = if components.len() == 1 {
+              components[0].clone()
+            } else {
+              panic!("check this line of code yo");
+            };
+            Subpattern {
+              tag: None,
+              subpatterns: vec![],
+              guard: None,
+              bound_vars: vec![Some(name.clone())],
+            }
+          }
+        }
+      },
+    }
+  }
+}
+
+impl PatternLiteral {
+  fn to_subpattern(&self, _symbol_table: &SymbolTable) -> Subpattern {
+    use self::PatternLiteral::*;
+    match self {
+      NumPattern { neg, num } => {
+        let comparison = Expr::Lit(match (neg, num) {
+          (false, ExpressionKind::NatLiteral(n)) => Lit::Nat(*n),
+          (false, ExpressionKind::FloatLiteral(f)) => Lit::Float(*f),
+          (true, ExpressionKind::NatLiteral(n)) => Lit::Int(-1*(*n as i64)),
+          (true, ExpressionKind::FloatLiteral(f)) => Lit::Float(-1.0*f),
+          _ => panic!("This should never happen")
+        });
+        let guard = Some(Expr::Call {
+          f: Box::new(Expr::Func(Func::BuiltIn(Builtin::Equality))),
+          args: vec![comparison, Expr::ConditionalTargetSigilValue],
+        });
+        Subpattern {
+          tag: None,
+          subpatterns: vec![],
+          guard,
+          bound_vars: vec![],
+        }
+      },
+      StringPattern(s) => {
+        let guard = Some(Expr::Call {
+          f: Box::new(Expr::Func(Func::BuiltIn(Builtin::Equality))),
+          args: vec![Expr::Lit(Lit::StringLit(s.clone())), Expr::ConditionalTargetSigilValue]
+        });
+
+        Subpattern {
+          tag: None,
+          subpatterns: vec![],
+          guard,
+          bound_vars: vec![],
+        }
+      },
+      BoolPattern(b) =>  {
+        let guard = Some(if *b {
+          Expr::ConditionalTargetSigilValue
+        } else {
+          Expr::Call {
+            f: Box::new(Expr::Func(Func::BuiltIn(Builtin::BooleanNot))),
+            args: vec![Expr::ConditionalTargetSigilValue]
+          }
+        });
+        Subpattern {
+          tag: None,
+          subpatterns: vec![],
+          guard,
+          bound_vars: vec![],
+        }
+      },
+    }
+  }
+
+}
--- a/schala-lang/language/src/schala.rs
+++ b/schala-lang/language/src/schala.rs
@ -0,0 +1,338 @@
+use stopwatch::Stopwatch;
+
+use std::time::Duration;
+use std::cell::RefCell;
+use std::rc::Rc;
+use std::collections::HashSet;
+
+use itertools::Itertools;
+use schala_repl::{ProgrammingLanguageInterface,
+ComputationRequest, ComputationResponse,
+LangMetaRequest, LangMetaResponse, GlobalOutputStats,
+DebugResponse, DebugAsk};
+use crate::{ast, reduced_ast, tokenizing, parsing, eval, typechecking, symbol_table, source_map};
+
+pub type SymbolTableHandle = Rc<RefCell<symbol_table::SymbolTable>>;
+pub type SourceMapHandle = Rc<RefCell<source_map::SourceMap>>;
+
+/// All the state necessary to parse and execute a Schala program are stored in this struct.
+/// `state` represents the execution state for the AST-walking interpreter, the other fields
+/// should be self-explanatory.
+pub struct Schala {
+  source_reference: SourceReference,
+  source_map: SourceMapHandle,
+  state: eval::State<'static>,
+  symbol_table: SymbolTableHandle,
+  resolver: crate::scope_resolution::ScopeResolver<'static>,
+  type_context: typechecking::TypeContext<'static>,
+  active_parser: parsing::Parser,
+}
+
+impl Schala {
+  fn handle_docs(&self, source: String) -> LangMetaResponse {
+    LangMetaResponse::Docs {
+      doc_string: format!("Schala item `{}` : <<Schala-lang documentation not yet implemented>>", source)
+    }
+  }
+}
+
+impl Schala {
+  /// Creates a new Schala environment *without* any prelude.
+  fn new_blank_env() -> Schala {
+    let source_map = Rc::new(RefCell::new(source_map::SourceMap::new()));
+    let symbols = Rc::new(RefCell::new(symbol_table::SymbolTable::new(source_map.clone())));
+    Schala {
+      //TODO maybe these can be the same structure
+      source_reference: SourceReference::new(),
+      symbol_table: symbols.clone(),
+      source_map: source_map.clone(),
+      resolver: crate::scope_resolution::ScopeResolver::new(symbols.clone()),
+      state: eval::State::new(),
+      type_context: typechecking::TypeContext::new(),
+      active_parser: parsing::Parser::new(source_map)
+    }
+  }
+
+  /// Creates a new Schala environment with the standard prelude, which is defined as ordinary
+  /// Schala code in the file `prelude.schala`
+  pub fn new() -> Schala {
+    let prelude = include_str!("prelude.schala");
+    let mut s = Schala::new_blank_env();
+
+    let request = ComputationRequest { source: prelude, debug_requests: HashSet::default() };
+    let response = s.run_computation(request);
+    if let Err(msg) = response.main_output {
+      panic!("Error in prelude, panicking: {}", msg);
+    }
+    s
+  }
+
+  fn handle_debug_immediate(&self, request: DebugAsk) -> DebugResponse {
+    use DebugAsk::*;
+    match request {
+      Timing => DebugResponse { ask: Timing, value: format!("Invalid") },
+      ByStage { stage_name, token } => match &stage_name[..] {
+        "symbol-table" => {
+          let value = self.symbol_table.borrow().debug_symbol_table();
+          DebugResponse {
+            ask: ByStage { stage_name: format!("symbol-table"), token },
+            value
+          }
+        },
+        s => {
+          DebugResponse {
+            ask: ByStage { stage_name: s.to_string(), token: None },
+            value: format!("Not-implemented")
+          }
+        }
+      }
+    }
+  }
+}
+
+fn tokenizing(input: &str, _handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<Vec<tokenizing::Token>, String> {
+  let tokens = tokenizing::tokenize(input);
+  comp.map(|comp| {
+    let token_string = tokens.iter().map(|t| t.to_string_with_metadata()).join(", ");
+    comp.add_artifact(token_string);
+  });
+
+  let errors: Vec<String> = tokens.iter().filter_map(|t| t.get_error()).collect();
+  if errors.len() == 0 {
+    Ok(tokens)
+  } else {
+    Err(format!("{:?}", errors))
+  }
+}
+
+fn parsing(input: Vec<tokenizing::Token>, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<ast::AST, String> {
+  use ParsingDebugType::*;
+
+  let ref mut parser = handle.active_parser;
+  parser.add_new_tokens(input);
+  let ast = parser.parse();
+
+  comp.map(|comp| {
+    let debug_format = comp.parsing.as_ref().unwrap_or(&CompactAST);
+    let debug_info = match debug_format {
+      CompactAST => match ast{
+        Ok(ref ast) => ast.compact_debug(),
+        Err(_) => "Error - see output".to_string(),
+      },
+      ExpandedAST => match ast{
+        Ok(ref ast) => ast.expanded_debug(),
+        Err(_) => "Error - see output".to_string(),
+      },
+      Trace => parser.format_parse_trace(),
+    };
+    comp.add_artifact(debug_info);
+  });
+  ast.map_err(|err| format_parse_error(err, &handle.source_reference))
+}
+
+fn format_parse_error(error: parsing::ParseError, source_reference: &SourceReference) -> String {
+  let line_num = error.token.location.line_num;
+  let ch = error.token.location.char_num;
+  let line_from_program = source_reference.get_line(line_num);
+  let location_pointer = format!("{}^", " ".repeat(ch));
+
+  let line_num_digits = format!("{}", line_num).chars().count();
+  let space_padding = " ".repeat(line_num_digits);
+
+  let production = match error.production_name {
+    Some(n) => format!("\n(from production \"{}\")", n),
+    None => "".to_string()
+  };
+
+  format!(r#"
+{error_msg}{production}
+{space_padding} |
+{line_num} | {}
+{space_padding} | {}
+"#, line_from_program, location_pointer, error_msg=error.msg, space_padding=space_padding, line_num=line_num, production=production
+)
+}
+
+fn symbol_table(input: ast::AST, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<ast::AST, String> {
+  let () = handle.symbol_table.borrow_mut().add_top_level_symbols(&input)?;
+  comp.map(|comp| {
+    let debug = handle.symbol_table.borrow().debug_symbol_table();
+    comp.add_artifact(debug);
+  });
+  Ok(input)
+}
+
+fn scope_resolution(mut input: ast::AST, handle: &mut Schala, _com: Option<&mut PassDebugArtifact>) -> Result<ast::AST, String> {
+  let () = handle.resolver.resolve(&mut input)?;
+  Ok(input)
+}
+
+fn typechecking(input: ast::AST, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<ast::AST, String> {
+  let result = handle.type_context.typecheck(&input);
+
+  comp.map(|comp| {
+    comp.add_artifact(match result {
+      Ok(ty) => ty.to_string(),
+      Err(err) => format!("Type error: {}", err.msg)
+    });
+  });
+
+  Ok(input)
+}
+
+fn ast_reducing(input: ast::AST, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<reduced_ast::ReducedAST, String> {
+  let ref symbol_table = handle.symbol_table.borrow();
+  let output = reduced_ast::reduce(&input, symbol_table);
+  comp.map(|comp| comp.add_artifact(format!("{:?}", output)));
+  Ok(output)
+}
+
+fn eval(input: reduced_ast::ReducedAST, handle: &mut Schala, comp: Option<&mut PassDebugArtifact>) -> Result<String, String> {
+  comp.map(|comp| comp.add_artifact(handle.state.debug_print()));
+  let evaluation_outputs = handle.state.evaluate(input, true);
+  let text_output: Result<Vec<String>, String> = evaluation_outputs
+    .into_iter()
+    .collect();
+
+  let eval_output: Result<String, String> = text_output
+    .map(|v| { v.into_iter().intersperse(format!("\n")).collect() });
+  eval_output
+}
+
+/// Represents lines of source code
+struct SourceReference {
+  lines: Option<Vec<String>>
+}
+
+impl SourceReference {
+  fn new() -> SourceReference {
+    SourceReference { lines: None }
+  }
+
+  fn load_new_source(&mut self, source: &str) {
+    //TODO this is a lot of heap allocations - maybe there's a way to make it more efficient?
+    self.lines = Some(source.lines().map(|s| s.to_string()).collect()); }
+
+  fn get_line(&self, line: usize) -> String {
+    self.lines.as_ref().and_then(|x| x.get(line).map(|s| s.to_string())).unwrap_or(format!("NO LINE FOUND"))
+  }
+}
+
+enum ParsingDebugType {
+  CompactAST,
+  ExpandedAST,
+  Trace
+}
+
+#[derive(Default)]
+struct PassDebugArtifact {
+  parsing: Option<ParsingDebugType>,
+  artifacts: Vec<String>
+
+}
+impl PassDebugArtifact {
+  fn add_artifact(&mut self, artifact: String) {
+    self.artifacts.push(artifact)
+  }
+}
+
+fn stage_names() -> Vec<&'static str> {
+  vec![
+    "tokenizing",
+    "parsing",
+    "symbol-table",
+    "scope-resolution",
+    "typechecking",
+    "ast-reduction",
+    "ast-walking-evaluation"
+  ]
+}
+
+
+impl ProgrammingLanguageInterface for Schala {
+  fn get_language_name(&self) -> String { format!("Schala") }
+  fn get_source_file_suffix(&self) -> String { format!("schala") }
+
+  fn run_computation(&mut self, request: ComputationRequest) -> ComputationResponse {
+    struct PassToken<'a> {
+      schala: &'a mut Schala,
+      stage_durations: &'a mut Vec<(String, Duration)>,
+      sw: &'a Stopwatch,
+      debug_requests: &'a HashSet<DebugAsk>,
+      debug_responses: &'a mut Vec<DebugResponse>,
+    }
+
+    fn output_wrapper<Input, Output, F>(n: usize, func: F, input: Input, token: &mut PassToken) -> Result<Output, String>
+      where F: Fn(Input, &mut Schala, Option<&mut PassDebugArtifact>) -> Result<Output, String>
+    {
+      let stage_names = stage_names();
+      let cur_stage_name = stage_names[n];
+      let ask = token.debug_requests.iter().find(|ask| ask.is_for_stage(cur_stage_name));
+
+      let parsing = match ask {
+        Some(DebugAsk::ByStage { token, .. }) if cur_stage_name == "parsing" => Some(
+          token.as_ref().map(|token| match &token[..] {
+            "compact" => ParsingDebugType::CompactAST,
+            "expanded" => ParsingDebugType::ExpandedAST,
+            "trace" => ParsingDebugType::Trace,
+            _ => ParsingDebugType::CompactAST,
+          }).unwrap_or(ParsingDebugType::CompactAST)
+        ),
+        _ => None,
+      };
+
+      let mut debug_artifact = ask.map(|_| PassDebugArtifact {
+        parsing, ..Default::default()
+      });
+
+      let output = func(input, token.schala, debug_artifact.as_mut());
+
+      //TODO I think this is not counting the time since the *previous* stage
+      token.stage_durations.push((cur_stage_name.to_string(), token.sw.elapsed()));
+      if let Some(artifact) = debug_artifact {
+        for value in artifact.artifacts.into_iter() {
+          let resp = DebugResponse { ask: ask.unwrap().clone(), value };
+          token.debug_responses.push(resp);
+        }
+      }
+      output
+    }
+
+    let ComputationRequest { source, debug_requests } = request;
+    self.source_reference.load_new_source(source);
+    let sw = Stopwatch::start_new();
+    let mut stage_durations = Vec::new();
+    let mut debug_responses = Vec::new();
+    let mut tok = PassToken { schala: self, stage_durations: &mut stage_durations, sw: &sw, debug_requests: &debug_requests, debug_responses: &mut debug_responses };
+
+    let main_output: Result<String, String> = Ok(source)
+      .and_then(|source| output_wrapper(0, tokenizing, source, &mut tok))
+      .and_then(|tokens| output_wrapper(1, parsing, tokens, &mut tok))
+      .and_then(|ast| output_wrapper(2, symbol_table, ast, &mut tok))
+      .and_then(|ast| output_wrapper(3, scope_resolution, ast, &mut tok))
+      .and_then(|ast| output_wrapper(4, typechecking, ast, &mut tok))
+      .and_then(|ast| output_wrapper(5, ast_reducing, ast, &mut tok))
+      .and_then(|reduced_ast| output_wrapper(6, eval, reduced_ast, &mut tok));
+
+    let total_duration = sw.elapsed();
+    let global_output_stats = GlobalOutputStats {
+      total_duration, stage_durations
+    };
+
+    ComputationResponse {
+      main_output,
+      global_output_stats,
+      debug_responses,
+    }
+  }
+
+  fn request_meta(&mut self, request: LangMetaRequest) -> LangMetaResponse {
+    match request {
+      LangMetaRequest::StageNames => LangMetaResponse::StageNames(stage_names().iter().map(|s| s.to_string()).collect()),
+      LangMetaRequest::Docs { source } => self.handle_docs(source),
+      LangMetaRequest::ImmediateDebug(debug_request) =>
+        LangMetaResponse::ImmediateDebug(self.handle_debug_immediate(debug_request)),
+      LangMetaRequest::Custom { .. } => LangMetaResponse::Custom { kind: format!("not-implemented"), value: format!("") }
+    }
+  }
+}
--- a/schala-lang/language/src/scope_resolution.rs
+++ b/schala-lang/language/src/scope_resolution.rs
@ -0,0 +1,119 @@
+use std::rc::Rc;
+
+use crate::schala::SymbolTableHandle;
+use crate::symbol_table::{ScopeSegment, FullyQualifiedSymbolName};
+use crate::ast::*;
+use crate::util::ScopeStack;
+
+type FQSNPrefix = Vec<ScopeSegment>;
+
+pub struct ScopeResolver<'a> {
+  symbol_table_handle: SymbolTableHandle,
+  name_scope_stack: ScopeStack<'a, Rc<String>, FQSNPrefix>,
+}
+
+impl<'a> ASTVisitor for ScopeResolver<'a> {
+  //TODO need to un-insert these - maybe need to rethink visitor
+  fn import(&mut self, import_spec: &ImportSpecifier) {
+    let ref symbol_table = self.symbol_table_handle.borrow();
+    let ImportSpecifier { ref path_components, ref imported_names, .. } = &import_spec;
+    match imported_names {
+      ImportedNames::All => {
+        let prefix = FullyQualifiedSymbolName(path_components.iter().map(|c| ScopeSegment {
+          name: c.clone(),
+        }).collect());
+        let members = symbol_table.lookup_children_of_fqsn(&prefix);
+        for member in members.into_iter() {
+          let local_name = member.0.last().unwrap().name.clone();
+          self.name_scope_stack.insert(local_name.clone(), member.0);
+        }
+      },
+      ImportedNames::LastOfPath => {
+        let name = path_components.last().unwrap(); //TODO handle better
+        let fqsn_prefix = path_components.iter().map(|c| ScopeSegment {
+          name: c.clone(),
+        }).collect();
+        self.name_scope_stack.insert(name.clone(), fqsn_prefix);
+      }
+      ImportedNames::List(ref names) => {
+        let fqsn_prefix: FQSNPrefix = path_components.iter().map(|c| ScopeSegment {
+          name: c.clone(),
+        }).collect();
+        for name in names.iter() {
+          self.name_scope_stack.insert(name.clone(), fqsn_prefix.clone());
+        }
+      }
+    };
+  }
+
+  fn qualified_name(&mut self, qualified_name: &QualifiedName) {
+    let ref mut symbol_table = self.symbol_table_handle.borrow_mut();
+    let fqsn = self.lookup_name_in_scope(&qualified_name);
+    let ref id = qualified_name.id;
+    symbol_table.map_id_to_fqsn(id, fqsn);
+  }
+
+  fn named_struct(&mut self, name: &QualifiedName, _fields: &Vec<(Rc<String>, Expression)>) {
+    let ref mut symbol_table = self.symbol_table_handle.borrow_mut();
+    let ref id = name.id;
+    let fqsn = self.lookup_name_in_scope(&name);
+    symbol_table.map_id_to_fqsn(id, fqsn);
+  }
+
+  fn pattern(&mut self, pat: &Pattern) {
+    use Pattern::*;
+    match pat {
+      Ignored => (),
+      TuplePattern(_) => (),
+      Literal(_) => (),
+      TupleStruct(name, _) => self.qualified_name_in_pattern(name),
+      Record(name, _) => self.qualified_name_in_pattern(name),
+      VarOrName(name) => self.qualified_name_in_pattern(name),
+    };
+  }
+}
+
+impl<'a> ScopeResolver<'a> {
+  pub fn new(symbol_table_handle: SymbolTableHandle) -> ScopeResolver<'static> {
+    let name_scope_stack = ScopeStack::new(None);
+    ScopeResolver { symbol_table_handle, name_scope_stack }
+  }
+  pub fn resolve(&mut self, ast: &mut AST) -> Result<(), String> {
+    walk_ast(self, ast);
+    Ok(())
+  }
+
+  fn lookup_name_in_scope(&self, sym_name: &QualifiedName) -> FullyQualifiedSymbolName {
+    let QualifiedName { components, .. } = sym_name;
+    let first_component = &components[0];
+    match self.name_scope_stack.lookup(first_component) {
+      None => {
+        FullyQualifiedSymbolName(components.iter().map(|name| ScopeSegment { name: name.clone() }).collect())
+      },
+      Some(fqsn_prefix) => {
+        let mut full_name = fqsn_prefix.clone();
+        let rest_of_name: FQSNPrefix = components[1..].iter().map(|name| ScopeSegment { name: name.clone() }).collect();
+        full_name.extend_from_slice(&rest_of_name);
+        FullyQualifiedSymbolName(full_name)
+      }
+    }
+  }
+
+  /// this might be a variable or a pattern. if a variable, set to none
+  fn qualified_name_in_pattern(&mut self, qualified_name: &QualifiedName) {
+    let ref mut symbol_table = self.symbol_table_handle.borrow_mut();
+    let ref id = qualified_name.id;
+    let fqsn = self.lookup_name_in_scope(qualified_name);
+    if symbol_table.lookup_by_fqsn(&fqsn).is_some() {
+      symbol_table.map_id_to_fqsn(&id, fqsn);
+    }
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  #[test]
+  fn basic_scope() {
+
+  }
+}
--- a/schala-lang/language/src/source_map.rs
+++ b/schala-lang/language/src/source_map.rs
@ -0,0 +1,39 @@
+use std::collections::HashMap;
+use std::fmt;
+
+use crate::ast::ItemId;
+
+pub type LineNumber = usize;
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct Location {
+  pub line_num: LineNumber,
+  pub char_num: usize,
+}
+
+impl fmt::Display for Location {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    write!(f, "{}:{}", self.line_num, self.char_num)
+  }
+}
+
+pub struct SourceMap {
+  map: HashMap<ItemId, Location>
+}
+
+impl SourceMap {
+  pub fn new() -> SourceMap {
+    SourceMap { map: HashMap::new() }
+  }
+
+  pub fn add_location(&mut self, id: &ItemId, loc: Location) {
+    self.map.insert(id.clone(), loc);
+  }
+
+  pub fn lookup(&self, id: &ItemId) -> Option<Location> {
+    match self.map.get(id) {
+      Some(loc) => Some(loc.clone()),
+      None => None
+    }
+  }
+}
--- a/schala-lang/language/src/symbol_table.rs
+++ b/schala-lang/language/src/symbol_table.rs
@ -0,0 +1,343 @@
+use std::collections::HashMap;
+use std::collections::hash_map::Entry;
+use std::rc::Rc;
+use std::fmt;
+use std::fmt::Write;
+
+use crate::schala::SourceMapHandle;
+use crate::source_map::{SourceMap, LineNumber};
+use crate::ast;
+use crate::ast::{ItemId, TypeBody, TypeSingletonName, Signature, Statement, StatementKind, ModuleSpecifier};
+use crate::typechecking::TypeName;
+
+
+#[allow(unused_macros)]
+macro_rules! fqsn {
+  ( $( $name:expr ; $kind:tt),* ) => {
+    {
+      let mut vec = vec![];
+      $(
+        vec.push(crate::symbol_table::ScopeSegment::new(std::rc::Rc::new($name.to_string())));
+      )*
+      FullyQualifiedSymbolName(vec)
+    }
+  };
+}
+
+mod symbol_trie;
+use symbol_trie::SymbolTrie;
+mod test;
+
+/// Keeps track of what names were used in a given namespace. Call try_register to add a name to
+/// the table, or report an error if a name already exists.
+struct DuplicateNameTrackTable {
+  table: HashMap<Rc<String>, LineNumber>,
+}
+
+impl DuplicateNameTrackTable {
+  fn new() -> DuplicateNameTrackTable {
+    DuplicateNameTrackTable { table: HashMap::new() }
+  }
+
+  fn try_register(&mut self, name: &Rc<String>, id: &ItemId, source_map: &SourceMap) -> Result<(), LineNumber> {
+    match self.table.entry(name.clone()) {
+      Entry::Occupied(o) => {
+        let line_number = o.get();
+        Err(*line_number)
+      },
+      Entry::Vacant(v) => {
+        let line_number = if let Some(loc) = source_map.lookup(id) {
+          loc.line_num
+        } else {
+          0
+        };
+        v.insert(line_number);
+        Ok(())
+      }
+    }
+  }
+}
+
+#[derive(PartialEq, Eq, Hash, Debug, Clone, PartialOrd, Ord)]
+pub struct FullyQualifiedSymbolName(pub Vec<ScopeSegment>);
+
+impl fmt::Display for FullyQualifiedSymbolName {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    let FullyQualifiedSymbolName(v) = self;
+    for segment in v {
+      write!(f, "::{}", segment)?;
+    }
+    Ok(())
+  }
+}
+
+#[derive(Debug, Clone, Eq, PartialEq, Hash, PartialOrd, Ord)]
+pub struct ScopeSegment {
+  pub name: Rc<String>, //TODO maybe this could be a &str, for efficiency?
+}
+
+impl fmt::Display for ScopeSegment {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    let kind = ""; //TODO implement some kind of kind-tracking here
+    write!(f, "{}{}", self.name, kind)
+  }
+}
+
+impl ScopeSegment {
+  pub fn new(name: Rc<String>) ->  ScopeSegment {
+    ScopeSegment { name }
+  }
+}
+
+
+//cf. p. 150 or so of Language Implementation Patterns
+pub struct SymbolTable {
+  source_map_handle: SourceMapHandle,
+  symbol_path_to_symbol: HashMap<FullyQualifiedSymbolName, Symbol>,
+  id_to_fqsn: HashMap<ItemId, FullyQualifiedSymbolName>,
+  symbol_trie: SymbolTrie,
+}
+
+impl SymbolTable {
+  pub fn new(source_map_handle: SourceMapHandle) -> SymbolTable {
+    SymbolTable {
+      source_map_handle,
+      symbol_path_to_symbol: HashMap::new(),
+      id_to_fqsn: HashMap::new(),
+      symbol_trie: SymbolTrie::new()
+    }
+  }
+
+  pub fn map_id_to_fqsn(&mut self, id: &ItemId, fqsn: FullyQualifiedSymbolName) {
+    self.id_to_fqsn.insert(id.clone(), fqsn);
+  }
+
+  pub fn get_fqsn_from_id(&self, id: &ItemId) -> Option<FullyQualifiedSymbolName> {
+    self.id_to_fqsn.get(&id).cloned()
+  }
+
+  fn add_new_symbol(&mut self, local_name: &Rc<String>, scope_path: &Vec<ScopeSegment>, spec: SymbolSpec) {
+    let mut vec: Vec<ScopeSegment> = scope_path.clone();
+    vec.push(ScopeSegment { name: local_name.clone() });
+    let fully_qualified_name = FullyQualifiedSymbolName(vec);
+    let symbol = Symbol { local_name: local_name.clone(), fully_qualified_name: fully_qualified_name.clone(), spec };
+    self.symbol_trie.insert(&fully_qualified_name);
+    self.symbol_path_to_symbol.insert(fully_qualified_name, symbol);
+  }
+
+  pub fn lookup_by_fqsn(&self, fully_qualified_path: &FullyQualifiedSymbolName) -> Option<&Symbol> {
+    self.symbol_path_to_symbol.get(fully_qualified_path)
+  }
+
+  pub fn lookup_children_of_fqsn(&self, path: &FullyQualifiedSymbolName) -> Vec<FullyQualifiedSymbolName> {
+    self.symbol_trie.get_children(path)
+  }
+}
+
+#[derive(Debug)]
+pub struct Symbol {
+  pub local_name: Rc<String>, //TODO does this need to be pub?
+  fully_qualified_name: FullyQualifiedSymbolName,
+  pub spec: SymbolSpec,
+}
+
+impl fmt::Display for Symbol {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    write!(f, "<Local name: {}, Spec: {}>", self.local_name, self.spec)
+  }
+}
+
+#[derive(Debug)]
+pub enum SymbolSpec {
+  Func(Vec<TypeName>),
+  DataConstructor {
+    index: usize,
+    type_name: TypeName,
+    type_args: Vec<Rc<String>>,
+  },
+  RecordConstructor {
+    index: usize,
+    members: HashMap<Rc<String>, TypeName>,
+    type_name: TypeName,
+  },
+  Binding,
+  Type {
+    name: TypeName
+  },
+}
+
+impl fmt::Display for SymbolSpec {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    use self::SymbolSpec::*;
+    match self {
+      Func(type_names) => write!(f, "Func({:?})", type_names),
+      DataConstructor { index, type_name, type_args } => write!(f, "DataConstructor(idx: {})({:?} -> {})", index, type_args, type_name),
+      RecordConstructor { type_name, index, ..} => write!(f, "RecordConstructor(idx: {})(<members> -> {})", index, type_name),
+      Binding => write!(f, "Binding"),
+      Type { name } => write!(f, "Type <{}>", name),
+    }
+  }
+}
+
+impl SymbolTable {
+  /* note: this adds names for *forward reference* but doesn't actually create any types. solve that problem
+   * later */
+
+  pub fn add_top_level_symbols(&mut self, ast: &ast::AST) -> Result<(), String> {
+    let mut scope_name_stack = Vec::new();
+    self.add_symbols_from_scope(&ast.statements, &mut scope_name_stack)
+  }
+
+  fn add_symbols_from_scope<'a>(&'a mut self, statements: &Vec<Statement>, scope_name_stack: &mut Vec<ScopeSegment>) -> Result<(), String> {
+    use self::ast::Declaration::*;
+
+    let mut seen_identifiers = DuplicateNameTrackTable::new();
+    let mut seen_modules = DuplicateNameTrackTable::new();
+
+    for statement in statements.iter() {
+      match statement {
+        Statement { kind: StatementKind::Declaration(decl), id } => {
+          match decl {
+            FuncSig(ref signature) => {
+              seen_identifiers.try_register(&signature.name, &id, &self.source_map_handle.borrow())
+                .map_err(|line| format!("Duplicate function definition: {}. It's already defined at {}", signature.name, line))?;
+              self.add_function_signature(signature, scope_name_stack)?
+            }
+            FuncDecl(ref signature, ref body) => {
+              seen_identifiers.try_register(&signature.name, &id, &self.source_map_handle.borrow())
+                .map_err(|line| format!("Duplicate function definition: {}. It's already defined at {}", signature.name, line))?;
+              self.add_function_signature(signature, scope_name_stack)?;
+              scope_name_stack.push(ScopeSegment{
+                name: signature.name.clone(),
+              });
+              let output = self.add_symbols_from_scope(body, scope_name_stack);
+              scope_name_stack.pop();
+              output?
+            },
+            TypeDecl { name, body, mutable } => {
+              seen_identifiers.try_register(&name.name, &id, &self.source_map_handle.borrow())
+                .map_err(|line| format!("Duplicate type definition: {}. It's already defined at {}", name.name, line))?;
+              self.add_type_decl(name, body, mutable, scope_name_stack)?
+            },
+            Binding { name, .. } => {
+              seen_identifiers.try_register(&name, &id, &self.source_map_handle.borrow())
+                .map_err(|line| format!("Duplicate variable definition: {}. It's already defined at {}", name, line))?;
+              self.add_new_symbol(name, scope_name_stack, SymbolSpec::Binding);
+            }
+            _ => ()
+          }
+        },
+        Statement { kind: StatementKind::Module(ModuleSpecifier { name, contents}), id } => {
+          seen_modules.try_register(&name, &id, &self.source_map_handle.borrow())
+            .map_err(|line| format!("Duplicate module definition: {}. It's already defined at {}", name, line))?;
+          scope_name_stack.push(ScopeSegment { name: name.clone() });
+          let output = self.add_symbols_from_scope(contents, scope_name_stack);
+          scope_name_stack.pop();
+          output?
+        },
+        _ => ()
+      }
+    }
+    Ok(())
+  }
+  pub fn debug_symbol_table(&self) -> String {
+    let mut output = format!("Symbol table\n");
+    let mut sorted_symbols: Vec<(&FullyQualifiedSymbolName, &Symbol)> = self.symbol_path_to_symbol.iter().collect();
+    sorted_symbols.sort_by(|(fqsn, _), (other_fqsn, _)| fqsn.cmp(other_fqsn));
+    for (name, sym) in sorted_symbols.iter() {
+      write!(output, "{} -> {}\n", name, sym).unwrap();
+    }
+    output
+  }
+
+  fn add_function_signature(&mut self, signature: &Signature, scope_name_stack: &mut Vec<ScopeSegment>) -> Result<(), String> {
+    let mut local_type_context = LocalTypeContext::new();
+    let types = signature.params.iter().map(|param| match param.anno {
+      Some(ref type_identifier) => Rc::new(format!("{:?}", type_identifier)),
+      None => local_type_context.new_universal_type()
+    }).collect();
+    self.add_new_symbol(&signature.name, scope_name_stack, SymbolSpec::Func(types));
+    Ok(())
+  }
+
+  //TODO handle type mutability
+  fn add_type_decl(&mut self, type_name: &TypeSingletonName, body: &TypeBody, _mutable: &bool, scope_name_stack: &mut Vec<ScopeSegment>) -> Result<(), String> {
+    use crate::ast::{TypeIdentifier, Variant};
+    let TypeBody(variants) = body;
+    let ref type_name = type_name.name;
+
+
+    let type_spec = SymbolSpec::Type {
+      name: type_name.clone(),
+    };
+    self.add_new_symbol(type_name, &scope_name_stack, type_spec);
+
+    scope_name_stack.push(ScopeSegment{
+      name: type_name.clone(),
+    });
+    //TODO figure out why _params isn't being used here
+    for (index, var) in variants.iter().enumerate() {
+      match var {
+        Variant::UnitStruct(variant_name) => {
+          let spec = SymbolSpec::DataConstructor {
+            index,
+            type_name: type_name.clone(),
+            type_args: vec![],
+          };
+          self.add_new_symbol(variant_name, scope_name_stack, spec);
+        },
+        Variant::TupleStruct(variant_name, tuple_members) => {
+          //TODO fix the notion of a tuple type
+          let type_args = tuple_members.iter().map(|type_name| match type_name {
+            TypeIdentifier::Singleton(TypeSingletonName { name, ..}) => name.clone(),
+            TypeIdentifier::Tuple(_) => unimplemented!(),
+          }).collect();
+          let spec = SymbolSpec::DataConstructor {
+            index,
+            type_name: type_name.clone(),
+            type_args
+          };
+          self.add_new_symbol(variant_name, scope_name_stack, spec);
+        },
+        Variant::Record { name, members: defined_members } => {
+          let mut members = HashMap::new();
+          let mut duplicate_member_definitions = Vec::new();
+          for (member_name, member_type) in defined_members {
+            match members.entry(member_name.clone()) {
+              Entry::Occupied(_) => duplicate_member_definitions.push(member_name.clone()),
+              Entry::Vacant(v) => {
+                v.insert(match member_type {
+                  TypeIdentifier::Singleton(TypeSingletonName { name, ..}) => name.clone(),
+                  TypeIdentifier::Tuple(_) => unimplemented!(),
+                });
+              }
+            }
+          }
+          if duplicate_member_definitions.len() != 0 {
+            return Err(format!("Duplicate member(s) in definition of type {}: {:?}", type_name, duplicate_member_definitions));
+          }
+          let spec = SymbolSpec::RecordConstructor { index, type_name: type_name.clone(), members };
+          self.add_new_symbol(name, scope_name_stack, spec);
+        },
+      }
+    }
+    scope_name_stack.pop();
+    Ok(())
+  }
+}
+
+struct LocalTypeContext {
+  state: u8
+}
+impl LocalTypeContext {
+  fn new() -> LocalTypeContext {
+    LocalTypeContext { state: 0 }
+  }
+
+  fn new_universal_type(&mut self) -> TypeName {
+    let n = self.state;
+    self.state += 1;
+    Rc::new(format!("{}", (('a' as u8) + n) as char))
+  }
+}
+
--- a/schala-lang/language/src/symbol_table/symbol_trie.rs
+++ b/schala-lang/language/src/symbol_table/symbol_trie.rs
@ -0,0 +1,51 @@
+use radix_trie::{Trie, TrieCommon, TrieKey};
+use super::FullyQualifiedSymbolName;
+use std::hash::{Hasher, Hash};
+use std::collections::hash_map::DefaultHasher;
+
+#[derive(Debug)]
+pub struct SymbolTrie(Trie<FullyQualifiedSymbolName, ()>);
+
+impl TrieKey for FullyQualifiedSymbolName {
+  fn encode_bytes(&self) -> Vec<u8> {
+    let mut hasher = DefaultHasher::new();
+    let mut output = vec![];
+    let FullyQualifiedSymbolName(scopes) = self;
+    for segment in scopes.iter() {
+      segment.name.as_bytes().hash(&mut hasher);
+      output.extend_from_slice(&hasher.finish().to_be_bytes());
+    }
+    output
+  }
+}
+
+impl SymbolTrie {
+  pub fn new() -> SymbolTrie {
+    SymbolTrie(Trie::new())
+  }
+
+  pub fn insert(&mut self, fqsn: &FullyQualifiedSymbolName) {
+    self.0.insert(fqsn.clone(), ());
+  }
+
+  pub fn get_children(&self, fqsn: &FullyQualifiedSymbolName) -> Vec<FullyQualifiedSymbolName> {
+    let subtrie = match self.0.subtrie(fqsn) {
+      Some(s) => s,
+      None => return vec![]
+    };
+    let output: Vec<FullyQualifiedSymbolName> = subtrie.keys().filter(|cur_key| **cur_key != *fqsn).map(|fqsn| fqsn.clone()).collect();
+    output
+  }
+}
+
+#[test]
+fn test_trie_insertion() {
+  let mut trie = SymbolTrie::new();
+
+  trie.insert(&fqsn!("unrelated"; ty, "thing"; tr));
+  trie.insert(&fqsn!("outer"; ty, "inner"; tr));
+  trie.insert(&fqsn!("outer"; ty, "inner"; ty, "still_inner"; tr));
+
+  let children = trie.get_children(&fqsn!("outer"; ty, "inner"; tr));
+  assert_eq!(children.len(), 1);
+}
--- a/schala-lang/language/src/symbol_table/test.rs
+++ b/schala-lang/language/src/symbol_table/test.rs
@ -0,0 +1,193 @@
+#![cfg(test)]
+use std::cell::RefCell;
+use std::rc::Rc;
+
+use super::*;
+use crate::util::quick_ast;
+
+fn add_symbols_from_source(src: &str) -> (SymbolTable, Result<(), String>) {
+  let (ast, source_map) = quick_ast(src);
+  let source_map = Rc::new(RefCell::new(source_map));
+  let mut symbol_table = SymbolTable::new(source_map);
+  let result = symbol_table.add_top_level_symbols(&ast);
+  (symbol_table, result)
+}
+
+macro_rules! values_in_table {
+  ($source:expr, $single_value:expr) => {
+    values_in_table!($source => $single_value);
+  };
+  ($source:expr => $( $value:expr ),* ) => {
+    {
+    let (symbol_table, _) = add_symbols_from_source($source);
+    $(
+      match symbol_table.lookup_by_fqsn($value) {
+        Some(_spec) => (),
+        None => panic!(),
+      };
+    )*
+    }
+  };
+}
+
+#[test]
+fn basic_symbol_table() {
+  values_in_table! { "let a = 10; fn b() { 20 }", &fqsn!("b"; tr) };
+  values_in_table! { "type Option<T> = Some(T) | None" =>
+    &fqsn!("Option"; tr),
+    &fqsn!("Option"; ty, "Some"; tr),
+    &fqsn!("Option"; ty, "None"; tr) };
+}
+
+#[test]
+fn no_function_definition_duplicates() {
+  let source = r#"
+  fn a() { 1 }
+  fn b() { 2 }
+  fn a() { 3 }
+  "#;
+  let (_, output) = add_symbols_from_source(source);
+  assert!(output.unwrap_err().contains("Duplicate function definition: a"))
+}
+
+#[test]
+fn no_variable_definition_duplicates() {
+  let source = r#"
+  let x = 9
+  let a = 20
+  let q = 39
+  let a = 30
+  "#;
+  let (_, output) = add_symbols_from_source(source);
+  let output = output.unwrap_err();
+  assert!(output.contains("Duplicate variable definition: a"));
+  assert!(output.contains("already defined at 2"));
+}
+
+#[test]
+fn no_variable_definition_duplicates_in_function() {
+  let source = r#"
+  fn a() {
+    let a = 20
+    let b = 40
+    a + b
+  }
+
+  fn q() {
+    let a = 29
+    let x = 30
+    let x = 33
+  }
+  "#;
+  let (_, output) = add_symbols_from_source(source);
+  assert!(output.unwrap_err().contains("Duplicate variable definition: x"))
+}
+
+#[test]
+fn dont_falsely_detect_duplicates() {
+  let source = r#"
+  let a = 20;
+  fn some_func() {
+    let a = 40;
+    77
+  }
+  let q = 39;
+  "#;
+  let (symbol_table, _) = add_symbols_from_source(source);
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!["a"; tr]).is_some());
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!["some_func"; fn, "a";tr]).is_some());
+}
+
+#[test]
+fn enclosing_scopes() {
+  let source = r#"
+fn outer_func(x) {
+fn inner_func(arg) {
+  arg
+}
+x + inner_func(x)
+}"#;
+  let (symbol_table, _) = add_symbols_from_source(source);
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!("outer_func"; tr)).is_some());
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!("outer_func"; fn, "inner_func"; tr)).is_some());
+}
+
+#[test]
+fn enclosing_scopes_2() {
+  let source = r#"
+fn outer_func(x) {
+fn inner_func(arg) {
+  arg
+}
+
+fn second_inner_func() {
+  fn another_inner_func() {
+  }
+}
+
+inner_func(x)
+}"#;
+  let (symbol_table, _) = add_symbols_from_source(source);
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!("outer_func"; tr)).is_some());
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!("outer_func"; fn, "inner_func"; tr)).is_some());
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!("outer_func"; fn, "second_inner_func"; tr)).is_some());
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!("outer_func"; fn, "second_inner_func"; fn, "another_inner_func"; tr)).is_some());
+}
+
+#[test]
+fn enclosing_scopes_3() {
+  let source = r#"
+fn outer_func(x) {
+fn inner_func(arg) {
+  arg
+}
+
+fn second_inner_func() {
+  fn another_inner_func() {
+  }
+  fn another_inner_func() {
+  }
+}
+
+inner_func(x)
+}"#;
+  let (_, output) = add_symbols_from_source(source);
+  assert!(output.unwrap_err().contains("Duplicate"))
+}
+
+#[test]
+fn modules() {
+  let source = r#"
+module stuff {
+  fn item() {
+  }
+}
+
+fn item()
+"#;
+  values_in_table! { source  =>
+    &fqsn!("item"; tr),
+    &fqsn!("stuff"; tr, "item"; tr)
+  };
+}
+
+#[test]
+fn duplicate_modules() {
+  let source = r#"
+    module q {
+      fn foo() { 4 }
+    }
+
+    module a {
+      fn foo() { 334 }
+    }
+
+    module a {
+      fn foo() { 256.1 }
+    }
+    "#;
+  let (_, output) = add_symbols_from_source(source);
+  let output = output.unwrap_err();
+  assert!(output.contains("Duplicate module"));
+  assert!(output.contains("already defined at 5"));
+}
--- a/schala-lang/language/src/tokenizing.rs
+++ b/schala-lang/language/src/tokenizing.rs
@ -0,0 +1,344 @@
+use itertools::Itertools;
+use std::collections::HashMap;
+use std::rc::Rc;
+use std::iter::{Iterator, Peekable};
+use std::fmt;
+
+use crate::source_map::Location;
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum TokenKind {
+  Newline, Semicolon,
+
+  LParen, RParen,
+  LSquareBracket, RSquareBracket,
+  LAngleBracket, RAngleBracket,
+  LCurlyBrace, RCurlyBrace,
+  Pipe, Backslash,
+
+  Comma, Period, Colon, Underscore,
+  Slash, Equals,
+
+  Operator(Rc<String>),
+  DigitGroup(Rc<String>), HexLiteral(Rc<String>), BinNumberSigil,
+  StrLiteral {
+    s: Rc<String>,
+    prefix: Option<Rc<String>>
+  },
+  Identifier(Rc<String>),
+  Keyword(Kw),
+
+  EOF,
+
+  Error(String),
+}
+use self::TokenKind::*;
+
+impl fmt::Display for TokenKind {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    match self {
+      &Operator(ref s) => write!(f, "Operator({})", **s),
+      &DigitGroup(ref s) => write!(f, "DigitGroup({})", s),
+      &HexLiteral(ref s) => write!(f, "HexLiteral({})", s),
+      &StrLiteral {ref s, .. } => write!(f, "StrLiteral({})", s),
+      &Identifier(ref s) => write!(f, "Identifier({})", s),
+      &Error(ref s) => write!(f, "Error({})", s),
+      other => write!(f, "{:?}", other),
+    }
+  }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum Kw {
+  If, Then, Else,
+  Is,
+  Func,
+  For, While,
+  Const, Let, In,
+  Mut,
+  Return,
+  Alias, Type, SelfType, SelfIdent,
+  Interface, Impl,
+  True, False,
+  Module, Import
+}
+
+lazy_static! {
+  static ref KEYWORDS: HashMap<&'static str, Kw> =
+    hashmap! {
+      "if" => Kw::If,
+      "then" => Kw::Then,
+      "else" => Kw::Else,
+      "is" => Kw::Is,
+      "fn" => Kw::Func,
+      "for" => Kw::For,
+      "while" => Kw::While,
+      "const" => Kw::Const,
+      "let" => Kw::Let,
+      "in" => Kw::In,
+      "mut" => Kw::Mut,
+      "return" => Kw::Return,
+      "alias" => Kw::Alias,
+      "type" => Kw::Type,
+      "Self" => Kw::SelfType,
+      "self" => Kw::SelfIdent,
+      "interface" => Kw::Interface,
+      "impl" => Kw::Impl,
+      "true" => Kw::True,
+      "false" => Kw::False,
+      "module" => Kw::Module,
+      "import" => Kw::Import,
+    };
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct Token {
+  pub kind: TokenKind,
+  pub location: Location,
+}
+
+impl Token {
+  pub fn get_error(&self) -> Option<String> {
+    match self.kind {
+      TokenKind::Error(ref s) => Some(s.clone()),
+      _ => None,
+    }
+  }
+  pub fn to_string_with_metadata(&self) -> String {
+    format!("{}({})", self.kind, self.location)
+  }
+
+  pub fn get_kind(&self) -> TokenKind {
+    self.kind.clone()
+  }
+}
+
+const OPERATOR_CHARS: [char; 18] = ['!', '$', '%', '&', '*', '+', '-', '.', ':', '<', '>', '=', '?', '@', '^', '|', '~', '`'];
+fn is_operator(c: &char) -> bool {
+  OPERATOR_CHARS.iter().any(|x| x == c)
+}
+
+type CharData = (usize, usize, char);
+
+pub fn tokenize(input: &str) -> Vec<Token> {
+  let mut tokens: Vec<Token> = Vec::new();
+
+  let mut input = input.lines().enumerate()
+      .intersperse((0, "\n"))
+      .flat_map(|(line_idx, ref line)| {
+          line.chars().enumerate().map(move |(ch_idx, ch)| (line_idx, ch_idx, ch))
+      })
+      .peekable();
+
+  while let Some((line_num, char_num, c)) = input.next() {
+    let cur_tok_kind = match c {
+      '/' => match input.peek().map(|t| t.2) {
+        Some('/') => {
+          while let Some((_, _, c)) = input.next() {
+            if c == '\n' {
+              break;
+            }
+          }
+          continue;
+        },
+        Some('*') => {
+          input.next();
+          let mut comment_level = 1;
+          while let Some((_, _, c)) = input.next() {
+            if c == '*'  && input.peek().map(|t| t.2) == Some('/') {
+              input.next();
+              comment_level -= 1;
+            } else if c == '/' && input.peek().map(|t| t.2) == Some('*') {
+              input.next();
+              comment_level += 1;
+            }
+            if comment_level == 0 {
+              break;
+            }
+          }
+          continue;
+        },
+        _ => Slash
+      },
+      c if c.is_whitespace() && c != '\n' => continue,
+      '\n' => Newline, ';' => Semicolon,
+      ':' => Colon, ',' => Comma,
+      '(' => LParen, ')' => RParen,
+      '{' => LCurlyBrace, '}' => RCurlyBrace,
+      '[' => LSquareBracket, ']' => RSquareBracket,
+      '"' => handle_quote(&mut input, None),
+      '\\' => Backslash,
+      c if c.is_digit(10) => handle_digit(c, &mut input),
+      c if c.is_alphabetic() || c == '_' => handle_alphabetic(c, &mut input),
+      c if is_operator(&c) => handle_operator(c, &mut input),
+      unknown => Error(format!("Unexpected character: {}", unknown)),
+    };
+    let location = Location { line_num, char_num };
+    tokens.push(Token { kind: cur_tok_kind, location });
+  }
+  tokens
+}
+
+fn handle_digit(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenKind {
+  if c == '0' && input.peek().map_or(false, |&(_, _, c)| { c == 'x' }) {
+    input.next();
+    let rest: String = input.peeking_take_while(|&(_, _, ref c)| c.is_digit(16) || *c == '_').map(|(_, _, c)| { c }).collect();
+    HexLiteral(Rc::new(rest))
+  } else if c == '0' && input.peek().map_or(false, |&(_, _, c)| { c == 'b' }) {
+    input.next();
+    BinNumberSigil
+  } else {
+    let mut buf = c.to_string();
+    buf.extend(input.peeking_take_while(|&(_, _, ref c)| c.is_digit(10)).map(|(_, _, c)| { c }));
+    DigitGroup(Rc::new(buf))
+  }
+}
+
+fn handle_quote(input: &mut Peekable<impl Iterator<Item=CharData>>, quote_prefix: Option<&str>) -> TokenKind {
+  let mut buf = String::new();
+  loop {
+    match input.next().map(|(_, _, c)| { c }) {
+      Some('"') => break,
+      Some('\\') => {
+        let next = input.peek().map(|&(_, _, c)| { c });
+        if next == Some('n') {
+          input.next();
+          buf.push('\n')
+        } else if next == Some('"') {
+          input.next();
+          buf.push('"');
+        } else if next == Some('t') {
+          input.next();
+          buf.push('\t');
+        }
+      },
+      Some(c) => buf.push(c),
+      None => return TokenKind::Error(format!("Unclosed string")),
+    }
+  }
+  TokenKind::StrLiteral { s: Rc::new(buf), prefix: quote_prefix.map(|s| Rc::new(s.to_string())) }
+}
+
+fn handle_alphabetic(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenKind {
+  let mut buf = String::new();
+  buf.push(c);
+  if c == '_' && input.peek().map(|&(_, _, c)| { !c.is_alphabetic() }).unwrap_or(true) {
+    return TokenKind::Underscore
+  }
+
+  loop {
+    match input.peek().map(|&(_, _, c)| { c }) {
+      Some(c) if c == '"' => {
+        input.next();
+        return handle_quote(input, Some(&buf));
+      },
+      Some(c) if c.is_alphanumeric() || c == '_' => {
+        input.next();
+        buf.push(c);
+      },
+      _ => break,
+    }
+  }
+
+  match KEYWORDS.get(buf.as_str()) {
+    Some(kw) => TokenKind::Keyword(*kw),
+    None => TokenKind::Identifier(Rc::new(buf)),
+  }
+}
+
+fn handle_operator(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenKind {
+  match c {
+    '<' | '>' | '|' | '.' | '=' => {
+      let ref next = input.peek().map(|&(_, _, c)| { c });
+      if !next.map(|n| { is_operator(&n) }).unwrap_or(false) {
+        return match c {
+          '<' => LAngleBracket,
+          '>' => RAngleBracket,
+          '|' => Pipe,
+          '.' => Period,
+          '=' => Equals,
+          _ => unreachable!(),
+        }
+      }
+    },
+    _ => (),
+  };
+
+  let mut buf = String::new();
+
+  if c == '`' {
+    loop {
+      match input.peek().map(|&(_, _, c)| { c }) {
+        Some(c) if c.is_alphabetic() || c == '_' => {
+          input.next();
+          buf.push(c);
+        },
+        Some('`') => {
+          input.next();
+          break;
+        },
+        _ => break
+      }
+    }
+  } else {
+    buf.push(c);
+    loop {
+      match input.peek().map(|&(_, _, c)| { c }) {
+        Some(c) if is_operator(&c) => {
+          input.next();
+          buf.push(c);
+        },
+        _ => break
+      }
+    }
+  }
+  TokenKind::Operator(Rc::new(buf))
+}
+
+#[cfg(test)]
+mod schala_tokenizer_tests {
+  use super::*;
+  use super::Kw::*;
+
+  macro_rules! digit { ($ident:expr) => { DigitGroup(Rc::new($ident.to_string())) } }
+  macro_rules! ident { ($ident:expr) => { Identifier(Rc::new($ident.to_string())) } }
+  macro_rules! op { ($ident:expr) => { Operator(Rc::new($ident.to_string())) } }
+
+  #[test]
+  fn tokens() {
+    let a = tokenize("let a: A<B> = c ++ d");
+    let token_kinds: Vec<TokenKind> = a.into_iter().map(move |t| t.kind).collect();
+    assert_eq!(token_kinds, vec![Keyword(Let), ident!("a"), Colon, ident!("A"),
+      LAngleBracket, ident!("B"), RAngleBracket, Equals, ident!("c"), op!("++"), ident!("d")]);
+  }
+
+  #[test]
+  fn underscores() {
+    let token_kinds: Vec<TokenKind> = tokenize("4_8").into_iter().map(move |t| t.kind).collect();
+    assert_eq!(token_kinds, vec![digit!("4"), Underscore, digit!("8")]);
+
+    let token_kinds2: Vec<TokenKind> = tokenize("aba_yo").into_iter().map(move |t| t.kind).collect();
+    assert_eq!(token_kinds2, vec![ident!("aba_yo")]);
+  }
+
+  #[test]
+  fn comments() {
+    let token_kinds: Vec<TokenKind> = tokenize("1  + /* hella /* bro */ */ 2").into_iter().map(move |t| t.kind).collect();
+    assert_eq!(token_kinds, vec![digit!("1"), op!("+"), digit!("2")]);
+  }
+
+  #[test]
+  fn backtick_operators() {
+    let token_kinds: Vec<TokenKind> = tokenize("1 `plus` 2").into_iter().map(move |t| t.kind).collect();
+    assert_eq!(token_kinds, vec![digit!("1"), op!("plus"), digit!("2")]);
+  }
+
+  #[test]
+  fn string_literals() {
+    let token_kinds: Vec<TokenKind> = tokenize(r#""some string""#).into_iter().map(move |t| t.kind).collect();
+    assert_eq!(token_kinds, vec![StrLiteral { s: Rc::new("some string".to_string()), prefix: None }]);
+
+    let token_kinds: Vec<TokenKind> = tokenize(r#"b"some bytestring""#).into_iter().map(move |t| t.kind).collect();
+    assert_eq!(token_kinds, vec![StrLiteral { s: Rc::new("some bytestring".to_string()), prefix: Some(Rc::new("b".to_string())) }]);
+  }
+}
--- a/schala-lang/language/src/type_check.rs
+++ b/schala-lang/language/src/type_check.rs
--- a/schala-lang/language/src/typechecking.rs
+++ b/schala-lang/language/src/typechecking.rs
@ -1,10 +1,8 @@
 use std::rc::Rc;
-use std::convert::TryFrom;
-use std::fmt;
+use std::fmt::Write;

 use ena::unify::{UnifyKey, InPlaceUnificationTable, UnificationTable, EqUnifyValue};

-use crate::builtin::Builtin;
 use crate::ast::*;
 use crate::util::ScopeStack;
 use crate::util::deref_optional_box;
@ -22,31 +20,7 @@ impl TypeData {
  }
 }

-//TODO need to hook this into the actual typechecking system somehow
-#[derive(Debug, Clone)]
-pub struct TypeId {
-    local_name: Rc<String>
-}
-
-impl TypeId {
-    //TODO this is definitely incomplete
-    pub fn lookup_name(name: &str) -> TypeId {
-        TypeId {
-            local_name: Rc::new(name.to_string())
-        }
-    }
-
-    pub fn local_name(&self) -> &str {
-        self.local_name.as_ref()
-    }
-}
-
-impl fmt::Display for TypeId {
-  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-    write!(f, "TypeId:{}", self.local_name)
-  }
-}
-
+pub type TypeName = Rc<String>;

 pub struct TypeContext<'a> {
  variable_map: ScopeStack<'a, Rc<String>, Type>,
@ -103,21 +77,18 @@ pub enum TypeConst {
 }

 impl TypeConst {
-    /*
-  #[allow(dead_code)]
  pub fn to_string(&self) -> String {
    use self::TypeConst::*;
    match self {
-      Unit => "()".to_string(),
-      Nat => "Nat".to_string(),
-      Int => "Int".to_string(),
-      Float => "Float".to_string(),
-      StringT => "String".to_string(),
-      Bool => "Bool".to_string(),
-      Ordering => "Ordering".to_string(),
+      Unit => format!("()"),
+      Nat => format!("Nat"),
+      Int => format!("Int"),
+      Float => format!("Float"),
+      StringT => format!("String"),
+      Bool => format!("Bool"),
+      Ordering => format!("Ordering"),
    }
  }
-    */
 }

 impl EqUnifyValue for TypeConst { }
@ -136,15 +107,13 @@ macro_rules! ty {

 //TODO find a better way to capture the to/from string logic
 impl Type {
-    /*
-  #[allow(dead_code)]
  pub fn to_string(&self) -> String {
    use self::Type::*;
    match self {
      Const(c) => c.to_string(),
      Var(v) => format!("t_{}", v.0),
      Arrow { params, box ref ret } => {
-        if params.is_empty() {
+        if params.len() == 0 {
          format!("-> {}", ret.to_string())
        } else {
          let mut buf = String::new();
@ -155,10 +124,9 @@ impl Type {
          buf
        }
      },
-      Compound { .. } => "<some compound type>".to_string()
+      Compound { .. } => format!("<some compound type>")
    }
  }
-    */

  fn from_string(string: &str) -> Option<Type> {
    Some(match string {
@ -284,7 +252,7 @@ impl<'a> TypeContext<'a> {
    use self::TypeIdentifier::*;
    Ok(match name {
      Singleton(TypeSingletonName { name,.. }) =>  {
-        match Type::from_string(name) {
+        match Type::from_string(&name) {
          Some(ty) => ty,
          None => return TypeError::new(format!("Unknown type name: {}", name))
        }
@ -298,7 +266,7 @@ impl<'a> TypeContext<'a> {
  /// the AST to ReducedAST
  pub fn typecheck(&mut self, ast: &AST) -> Result<Type, TypeError> {
    let mut returned_type = Type::Const(TypeConst::Unit);
-    for statement in ast.statements.statements.iter() {
+    for statement in ast.statements.iter() {
      returned_type = self.statement(statement)?;
    }
    Ok(returned_type)
@ -307,7 +275,7 @@ impl<'a> TypeContext<'a> {
  fn statement(&mut self, statement: &Statement) -> InferResult<Type> {
    match &statement.kind {
      StatementKind::Expression(e) => self.expr(e),
-      StatementKind::Declaration(decl) => self.decl(decl),
+      StatementKind::Declaration(decl) => self.decl(&decl),
      StatementKind::Import(_) => Ok(ty!(Unit)),
      StatementKind::Module(_) => Ok(ty!(Unit)),
    }
@ -315,9 +283,12 @@ impl<'a> TypeContext<'a> {

  fn decl(&mut self, decl: &Declaration) -> InferResult<Type> {
    use self::Declaration::*;
-    if let Binding { name, expr, .. } = decl {
+    match decl {
+      Binding { name, expr, .. } => {
        let ty = self.expr(expr)?;
        self.variable_map.insert(name.clone(), ty);
+      },
+      _ => (),
    }
    Ok(ty!(Unit))
  }
@ -359,8 +330,7 @@ impl<'a> TypeContext<'a> {
  }

  fn prefix(&mut self, op: &PrefixOp, expr: &Expression) -> InferResult<Type> {
-    let builtin: Option<Builtin> = TryFrom::try_from(op).ok();
-    let tf = match builtin.map(|b| b.get_type()) {
+    let tf = match op.builtin.map(|b| b.get_type()) {
      Some(ty) => ty,
      None => return TypeError::new("no type found")
    };
@ -370,8 +340,7 @@ impl<'a> TypeContext<'a> {
  }

  fn binexp(&mut self, op: &BinOp, lhs: &Expression, rhs: &Expression) -> InferResult<Type> {
-    let builtin: Option<Builtin> = TryFrom::try_from(op).ok();
-    let tf = match builtin.map(|b| b.get_type()) {
+    let tf = match op.builtin.map(|b| b.get_type()) {
      Some(ty) => ty,
      None => return TypeError::new("no type found"),
    };
@ -386,11 +355,10 @@ impl<'a> TypeContext<'a> {
    use self::IfExpressionBody::*;
    match (discriminator, body) {
      (Some(expr), SimpleConditional{ then_case, else_case }) => self.handle_simple_if(expr, then_case, else_case),
-      _ => TypeError::new("Complex conditionals not supported".to_string())
+      _ => TypeError::new(format!("Complex conditionals not supported"))
    }
  }

-  #[allow(clippy::ptr_arg)]
  fn handle_simple_if(&mut self, expr: &Expression, then_clause: &Block, else_clause: &Option<Block>) -> InferResult<Type> {
    let t1 = self.expr(expr)?;
    let t2 = self.block(then_clause)?;
@ -403,7 +371,6 @@ impl<'a> TypeContext<'a> {
    self.unify(t2, t3)
  }

-  #[allow(clippy::ptr_arg)]
  fn lambda(&mut self, params: &Vec<FormalParam>, type_anno: &Option<TypeIdentifier>, _body: &Block) -> InferResult<Type> {
    let argument_types: InferResult<Vec<Type>> = params.iter().map(|param: &FormalParam| {
      if let FormalParam { anno: Some(type_identifier), ..  } = param {
@ -421,7 +388,7 @@ impl<'a> TypeContext<'a> {
    Ok(ty!(argument_types, ret_type))
  }

-  fn call(&mut self, f: &Expression, args: &[ InvocationArgument ]) -> InferResult<Type> {
+  fn call(&mut self, f: &Expression, args: &Vec<InvocationArgument>) -> InferResult<Type> {
    let tf = self.expr(f)?;
    let arg_types: InferResult<Vec<Type>> = args.iter().map(|ex| self.invoc(ex)).collect();
    let arg_types = arg_types?;
@ -437,14 +404,13 @@ impl<'a> TypeContext<'a> {
        t_ret.clone()
      },
      Type::Arrow { .. } => return TypeError::new("Wrong length"),
-      _ => return TypeError::new("Not a function".to_string())
+      _ => return TypeError::new(format!("Not a function"))
    })
  }

-  #[allow(clippy::ptr_arg)]
  fn block(&mut self, block: &Block) -> InferResult<Type> {
    let mut output = ty!(Unit);
-    for statement in block.statements.iter() {
+    for statement in block.iter() {
      output = self.statement(statement)?;
    }
    Ok(output)
@ -466,26 +432,26 @@ impl<'a> TypeContext<'a> {
      (Const(ref c1), Const(ref c2)) if c1 == c2 => Ok(Const(c1.clone())), //choice of c1 is arbitrary I *think*
      (a @ Var(_), b @ Const(_)) => self.unify(b, a),
      (Const(ref c1), Var(ref v2)) => {
-        self.unification_table.unify_var_value(*v2, Some(c1.clone()))
+        self.unification_table.unify_var_value(v2.clone(), Some(c1.clone()))
          .or_else(|_| TypeError::new(format!("Couldn't unify {:?} and {:?}", Const(c1.clone()), Var(*v2))))?;
        Ok(Const(c1.clone()))
      },
      (Var(v1), Var(v2)) => {
        //TODO add occurs check
-        self.unification_table.unify_var_var(v1, v2)
+        self.unification_table.unify_var_var(v1.clone(), v2.clone())
          .or_else(|e| {
            println!("Unify error: {:?}", e);
            TypeError::new(format!("Two type variables {:?} and {:?} couldn't unify", v1, v2))
          })?;
-        Ok(Var(v1)) //arbitrary decision I think
+        Ok(Var(v1.clone())) //arbitrary decision I think
      },
      (a, b) => TypeError::new(format!("{:?} and {:?} do not unify", a, b)),
    }
  }

  fn fresh_type_variable(&mut self) -> TypeVar {
-    
-    self.unification_table.new_key(None)
+    let new_type_var = self.unification_table.new_key(None);
+    new_type_var
  }
 }

@ -496,7 +462,7 @@ mod typechecking_tests {
  macro_rules! assert_type_in_fresh_context {
    ($string:expr, $type:expr) => {
      let mut tc = TypeContext::new();
-      let ast = &crate::util::quick_ast($string);
+      let (ref ast, _) = crate::util::quick_ast($string);
      let ty = tc.typecheck(ast).unwrap();
      assert_eq!(ty, $type)
    }
--- a/schala-lang/language/src/util.rs
+++ b/schala-lang/language/src/util.rs
@ -0,0 +1,68 @@
+use std::collections::HashMap;
+use std::hash::Hash;
+use std::cmp::Eq;
+use std::ops::Deref;
+
+pub fn deref_optional_box<T>(x: &Option<Box<T>>) -> Option<&T> {
+  x.as_ref().map(|b: &Box<T>| Deref::deref(b))
+}
+
+#[derive(Default, Debug)]
+pub struct ScopeStack<'a, T: 'a, V: 'a>  where T: Hash + Eq {
+  parent: Option<&'a ScopeStack<'a, T, V>>,
+  values: HashMap<T, V>,
+  scope_name: Option<String>
+}
+
+impl<'a, T, V> ScopeStack<'a, T, V> where T: Hash + Eq {
+  pub fn new(name: Option<String>) -> ScopeStack<'a, T, V> where T: Hash + Eq {
+    ScopeStack {
+      parent: None,
+      values: HashMap::new(),
+      scope_name: name
+    }
+  }
+  pub fn insert(&mut self, key: T, value: V) where T: Hash + Eq {
+    self.values.insert(key, value);
+  }
+  pub fn lookup(&self, key: &T) -> Option<&V> where T: Hash + Eq {
+    match (self.values.get(key), self.parent) {
+      (None, None) => None,
+      (None, Some(parent)) => parent.lookup(key),
+      (Some(value), _) => Some(value),
+    }
+  }
+
+  pub fn new_scope(&'a self, name: Option<String>) -> ScopeStack<'a, T, V> where T: Hash + Eq {
+    ScopeStack {
+      parent: Some(self),
+      values: HashMap::default(),
+      scope_name: name,
+    }
+  }
+  #[allow(dead_code)]
+  pub fn get_name(&self) -> Option<&String> {
+    self.scope_name.as_ref()
+  }
+}
+
+/// this is intended for use in tests, and does no error-handling whatsoever
+#[allow(dead_code)]
+pub fn quick_ast(input: &str) -> (crate::ast::AST, crate::source_map::SourceMap) {
+  use std::cell::RefCell;
+  use std::rc::Rc;
+
+  let source_map = crate::source_map::SourceMap::new();
+  let source_map_handle = Rc::new(RefCell::new(source_map));
+  let tokens = crate::tokenizing::tokenize(input);
+  let mut parser = crate::parsing::Parser::new(source_map_handle.clone());
+  parser.add_new_tokens(tokens);
+  let output = parser.parse();
+  std::mem::drop(parser);
+  (output.unwrap(), Rc::try_unwrap(source_map_handle).map_err(|_| ()).unwrap().into_inner())
+}
+
+#[allow(unused_macros)]
+macro_rules! rc {
+  ($string:tt) => { Rc::new(stringify!($string).to_string()) }
+}
--- a/schala-lang/src/ast/mod.rs
+++ b/schala-lang/src/ast/mod.rs
@ -1,345 +0,0 @@
-#![allow(clippy::upper_case_acronyms)]
-#![allow(clippy::enum_variant_names)]
-
-use std::{
-    convert::{AsRef, From},
-    fmt,
-    rc::Rc,
-};
-
-mod operators;
-mod visitor;
-mod visualize;
-
-pub use operators::{BinOp, PrefixOp};
-pub use visitor::*;
-
-use crate::{
-    derivative::Derivative,
-    identifier::{define_id_kind, Id},
-    parsing::Location,
-    util::delim_wrapped,
-};
-
-define_id_kind!(ASTItem);
-
-pub type ItemId = Id<ASTItem>;
-
-#[derive(Derivative, Debug)]
-#[derivative(PartialEq)]
-pub struct AST {
-    #[derivative(PartialEq = "ignore")]
-    pub id: ItemId,
-    pub statements: Block,
-}
-
-impl fmt::Display for AST {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}", visualize::render_ast(self))
-    }
-}
-
-#[derive(Derivative, Debug, Clone)]
-#[derivative(PartialEq)]
-pub struct Statement<K> {
-    #[derivative(PartialEq = "ignore")]
-    pub id: ItemId,
-    #[derivative(PartialEq = "ignore")]
-    pub location: Location,
-    pub kind: K,
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum StatementKind {
-    Expression(Expression),
-    Declaration(Declaration),
-    Import(ImportSpecifier),
-    Flow(FlowControl),
-}
-
-#[derive(Debug, Clone, PartialEq)]
-pub enum FlowControl {
-    Continue,
-    Break,
-    Return(Option<Expression>),
-}
-
-#[derive(Debug, Clone, PartialEq, Default)]
-pub struct Block {
-    pub statements: Vec<Statement<StatementKind>>,
-}
-
-impl From<Vec<Statement<StatementKind>>> for Block {
-    fn from(statements: Vec<Statement<StatementKind>>) -> Self {
-        Self { statements }
-    }
-}
-
-impl From<Statement<StatementKind>> for Block {
-    fn from(statement: Statement<StatementKind>) -> Self {
-        Self { statements: vec![statement] }
-    }
-}
-
-impl AsRef<[Statement<StatementKind>]> for Block {
-    fn as_ref(&self) -> &[Statement<StatementKind>] {
-        self.statements.as_ref()
-    }
-}
-
-pub type ParamName = Rc<String>;
-
-#[derive(Debug, Derivative, Clone)]
-#[derivative(PartialEq)]
-pub struct QualifiedName {
-    #[derivative(PartialEq = "ignore")]
-    pub id: ItemId,
-    pub components: Vec<Rc<String>>,
-}
-
-impl fmt::Display for QualifiedName {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match &self.components[..] {
-            [] => write!(f, "[<empty>]"),
-            [name] => write!(f, "{}", name),
-            [name, rest @ ..] => {
-                write!(f, "{}", name)?;
-                for c in rest {
-                    write!(f, "::{}", c)?;
-                }
-                Ok(())
-            }
-        }
-    }
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct FormalParam {
-    pub name: ParamName,
-    pub default: Option<Expression>,
-    pub anno: Option<TypeIdentifier>,
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum Declaration {
-    FuncSig(Signature),
-    FuncDecl(Signature, Block),
-    TypeDecl {
-        name: TypeSingletonName,
-        body: TypeBody,
-        mutable: bool,
-    },
-    //TODO TypeAlias `original` needs to be a more complex type definition
-    TypeAlias {
-        alias: Rc<String>,
-        original: Rc<String>,
-    },
-    Binding {
-        name: Rc<String>,
-        constant: bool,
-        type_anno: Option<TypeIdentifier>,
-        expr: Expression,
-    },
-    Impl {
-        type_name: TypeIdentifier,
-        interface_name: Option<TypeSingletonName>,
-        block: Vec<Statement<Declaration>>,
-    },
-    Interface {
-        name: Rc<String>,
-        signatures: Vec<Signature>,
-    },
-    //TODO need to limit the types of statements that can be annotated
-    Annotation {
-        name: Rc<String>,
-        arguments: Vec<Expression>,
-        inner: Box<Statement<StatementKind>>,
-    },
-    Module {
-        name: Rc<String>,
-        items: Block,
-    },
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct Signature {
-    pub name: Rc<String>,
-    pub operator: bool,
-    pub params: Vec<FormalParam>,
-    pub type_anno: Option<TypeIdentifier>,
-}
-
-//TODO I can probably get rid of TypeBody
-#[derive(Debug, Derivative, Clone)]
-#[derivative(PartialEq)]
-pub enum TypeBody {
-    Variants(Vec<Variant>),
-    ImmediateRecord {
-        #[derivative(PartialEq = "ignore")]
-        id: ItemId,
-        fields: Vec<(Rc<String>, TypeIdentifier)>,
-    },
-}
-
-#[derive(Debug, Derivative, Clone)]
-#[derivative(PartialEq)]
-pub struct Variant {
-    #[derivative(PartialEq = "ignore")]
-    pub id: ItemId,
-    pub name: Rc<String>,
-    pub kind: VariantKind,
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum VariantKind {
-    UnitStruct,
-    TupleStruct(Vec<TypeIdentifier>),
-    Record(Vec<(Rc<String>, TypeIdentifier)>),
-}
-
-#[derive(Debug, Derivative, Clone)]
-#[derivative(PartialEq)]
-pub struct Expression {
-    #[derivative(PartialEq = "ignore")]
-    pub id: ItemId,
-    pub kind: ExpressionKind,
-    //TODO this should only allow singletons, not tuples
-    pub type_anno: Option<TypeIdentifier>,
-}
-
-impl Expression {
-    pub fn new(id: ItemId, kind: ExpressionKind) -> Expression {
-        Expression { id, kind, type_anno: None }
-    }
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum TypeIdentifier {
-    Tuple(Vec<TypeIdentifier>),
-    Singleton(TypeSingletonName),
-}
-
-impl fmt::Display for TypeIdentifier {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match self {
-            TypeIdentifier::Tuple(items) =>
-                write!(f, "{}", delim_wrapped('(', ')', items.iter().map(|item| item.to_string()))),
-            TypeIdentifier::Singleton(tsn) => {
-                write!(f, "{}", tsn.name)?;
-                if !tsn.params.is_empty() {
-                    write!(f, "{}", delim_wrapped('<', '>', tsn.params.iter().map(|item| item.to_string())))?;
-                }
-                Ok(())
-            }
-        }
-    }
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct TypeSingletonName {
-    pub name: Rc<String>,
-    pub params: Vec<TypeIdentifier>,
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum ExpressionKind {
-    NatLiteral(u64),
-    FloatLiteral(f64),
-    StringLiteral { prefix: Option<Rc<String>>, s: Rc<String> },
-    BoolLiteral(bool),
-    BinExp(BinOp, Box<Expression>, Box<Expression>),
-    PrefixExp(PrefixOp, Box<Expression>),
-    TupleLiteral(Vec<Expression>),
-    Value(QualifiedName),
-    SelfValue,
-    NamedStruct { name: QualifiedName, fields: Vec<(Rc<String>, Expression)> },
-    Call { f: Box<Expression>, arguments: Vec<InvocationArgument> },
-    Index { indexee: Box<Expression>, indexers: Vec<Expression> },
-    IfExpression { discriminator: Option<Box<Expression>>, body: Box<IfExpressionBody> },
-    WhileExpression { condition: Option<Box<Expression>>, body: Block },
-    ForExpression { enumerators: Vec<Enumerator>, body: Box<ForBody> },
-    Lambda { params: Vec<FormalParam>, type_anno: Option<TypeIdentifier>, body: Block },
-    Access { name: Rc<String>, expr: Box<Expression> },
-    ListLiteral(Vec<Expression>),
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum InvocationArgument {
-    Positional(Expression),
-    Keyword { name: Rc<String>, expr: Expression },
-    Ignored,
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum IfExpressionBody {
-    SimpleConditional { then_case: Block, else_case: Option<Block> },
-    SimplePatternMatch { pattern: Pattern, then_case: Block, else_case: Option<Block> },
-    CondList(Vec<ConditionArm>),
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct ConditionArm {
-    pub condition: Condition,
-    pub guard: Option<Expression>,
-    pub body: Block,
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum Condition {
-    Pattern(Pattern),
-    TruncatedOp(BinOp, Expression),
-    //Expression(Expression), //I'm pretty sure I don't actually want this
-    Else,
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum Pattern {
-    Ignored,
-    TuplePattern(Vec<Pattern>),
-    Literal(PatternLiteral),
-    TupleStruct(QualifiedName, Vec<Pattern>),
-    Record(QualifiedName, Vec<(Rc<String>, Pattern)>),
-    VarOrName(QualifiedName),
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum PatternLiteral {
-    NumPattern { neg: bool, num: ExpressionKind },
-    StringPattern(Rc<String>),
-    BoolPattern(bool),
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct Enumerator {
-    pub identifier: Rc<String>,
-    pub generator: Expression,
-    pub assignment: bool, //true if `=`, false if `<-`
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum ForBody {
-    MonadicReturn(Expression),
-    StatementBlock(Block),
-}
-
-#[derive(Debug, Derivative, Clone)]
-#[derivative(PartialEq)]
-pub struct ImportSpecifier {
-    #[derivative(PartialEq = "ignore")]
-    pub id: ItemId,
-    pub path_components: Vec<Rc<String>>,
-    pub imported_names: ImportedNames,
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum ImportedNames {
-    All,
-    LastOfPath,
-    List(Vec<Rc<String>>),
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct ModuleSpecifier {
-    pub name: Rc<String>,
-    pub contents: Block,
-}
--- a/schala-lang/src/ast/operators.rs
+++ b/schala-lang/src/ast/operators.rs
@ -1,61 +0,0 @@
-use std::rc::Rc;
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct PrefixOp {
-    sigil: Rc<String>,
-}
-
-impl PrefixOp {
-    pub fn from_sigil(sigil: &str) -> PrefixOp {
-        PrefixOp { sigil: Rc::new(sigil.to_string()) }
-    }
-
-    pub fn sigil(&self) -> &str {
-        &self.sigil
-    }
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct BinOp {
-    sigil: Rc<String>,
-}
-
-impl BinOp {
-    pub fn from_sigil(sigil: &str) -> BinOp {
-        BinOp { sigil: Rc::new(sigil.to_string()) }
-    }
-
-    pub fn sigil(&self) -> &str {
-        &self.sigil
-    }
-
-    pub fn min_precedence() -> i32 {
-        i32::min_value()
-    }
-    pub fn get_precedence(&self) -> i32 {
-        binop_precedences(self.sigil.as_ref())
-    }
-}
-
-fn binop_precedences(s: &str) -> i32 {
-    let default = 10_000_000;
-    match s {
-        "+" => 10,
-        "-" => 10,
-        "*" => 20,
-        "/" => 20,
-        "%" => 20,
-        "++" => 30,
-        "^" => 30,
-        "&" => 20,
-        "|" => 20,
-        ">" => 20,
-        ">=" => 20,
-        "<" => 20,
-        "<=" => 20,
-        "==" => 40,
-        "<=>" => 30,
-        "=" => 5, // Assignment shoudl have highest precedence
-        _ => default,
-    }
-}
--- a/schala-lang/src/ast/visitor.rs
+++ b/schala-lang/src/ast/visitor.rs
@ -1,202 +0,0 @@
-use crate::ast::*;
-
-#[derive(Debug)]
-pub enum Recursion {
-    Continue,
-    Stop,
-}
-
-pub trait ASTVisitor: Sized {
-    fn expression(&mut self, _expression: &Expression) -> Recursion {
-        Recursion::Continue
-    }
-    fn declaration(&mut self, _declaration: &Declaration, _id: &ItemId) -> Recursion {
-        Recursion::Continue
-    }
-
-    fn import(&mut self, _import: &ImportSpecifier) -> Recursion {
-        Recursion::Continue
-    }
-    fn pattern(&mut self, _pat: &Pattern) -> Recursion {
-        Recursion::Continue
-    }
-}
-
-pub fn walk_ast<V: ASTVisitor>(v: &mut V, ast: &AST) {
-    walk_block(v, &ast.statements);
-}
-
-pub fn walk_block<V: ASTVisitor>(v: &mut V, block: &Block) {
-    use StatementKind::*;
-    for statement in block.statements.iter() {
-        match statement.kind {
-            StatementKind::Expression(ref expr) => {
-                walk_expression(v, expr);
-            }
-            Declaration(ref decl) => {
-                walk_declaration(v, decl, &statement.id);
-            }
-            Import(ref import_spec) => {
-                v.import(import_spec);
-            }
-            Flow(ref flow_control) =>
-                if let FlowControl::Return(Some(ref retval)) = flow_control {
-                    walk_expression(v, retval);
-                },
-        }
-    }
-}
-
-pub fn walk_declaration<V: ASTVisitor>(v: &mut V, decl: &Declaration, id: &ItemId) {
-    use Declaration::*;
-
-    if let Recursion::Continue = v.declaration(decl, id) {
-        match decl {
-            FuncDecl(_sig, block) => {
-                walk_block(v, block);
-            }
-            Binding { name: _, constant: _, type_anno: _, expr } => {
-                walk_expression(v, expr);
-            }
-            Module { name: _, items } => {
-                walk_block(v, items);
-            }
-            _ => (),
-        };
-    }
-}
-
-pub fn walk_expression<V: ASTVisitor>(v: &mut V, expr: &Expression) {
-    use ExpressionKind::*;
-
-    if let Recursion::Continue = v.expression(expr) {
-        match &expr.kind {
-            NatLiteral(_)
-            | FloatLiteral(_)
-            | StringLiteral { .. }
-            | BoolLiteral(_)
-            | Value(_)
-            | SelfValue => (),
-            BinExp(_, lhs, rhs) => {
-                walk_expression(v, lhs);
-                walk_expression(v, rhs);
-            }
-            PrefixExp(_, arg) => {
-                walk_expression(v, arg);
-            }
-            TupleLiteral(exprs) =>
-                for expr in exprs {
-                    walk_expression(v, expr);
-                },
-            NamedStruct { name: _, fields } =>
-                for (_, expr) in fields.iter() {
-                    walk_expression(v, expr);
-                },
-            Call { f, arguments } => {
-                walk_expression(v, f);
-                for arg in arguments.iter() {
-                    match arg {
-                        InvocationArgument::Positional(expr) | InvocationArgument::Keyword { expr, .. } =>
-                            walk_expression(v, expr),
-                        _ => (),
-                    }
-                }
-            }
-            Index { indexee, indexers } => {
-                walk_expression(v, indexee);
-                for indexer in indexers.iter() {
-                    walk_expression(v, indexer);
-                }
-            }
-            IfExpression { discriminator, body } => {
-                if let Some(d) = discriminator.as_ref() {
-                    walk_expression(v, d);
-                }
-                walk_if_expr_body(v, body.as_ref());
-            }
-            WhileExpression { condition, body } => {
-                if let Some(d) = condition.as_ref() {
-                    walk_expression(v, d);
-                }
-                walk_block(v, body);
-            }
-            ForExpression { enumerators, body } => {
-                for enumerator in enumerators {
-                    walk_expression(v, &enumerator.generator);
-                }
-                match body.as_ref() {
-                    ForBody::MonadicReturn(expr) => walk_expression(v, expr),
-                    ForBody::StatementBlock(block) => walk_block(v, block),
-                };
-            }
-            Lambda { params: _, type_anno: _, body } => {
-                walk_block(v, body);
-            }
-            Access { name: _, expr } => {
-                walk_expression(v, expr);
-            }
-            ListLiteral(exprs) =>
-                for expr in exprs {
-                    walk_expression(v, expr);
-                },
-        };
-    }
-}
-
-pub fn walk_if_expr_body<V: ASTVisitor>(v: &mut V, body: &IfExpressionBody) {
-    use IfExpressionBody::*;
-
-    match body {
-        SimpleConditional { then_case, else_case } => {
-            walk_block(v, then_case);
-            if let Some(block) = else_case.as_ref() {
-                walk_block(v, block)
-            }
-        }
-        SimplePatternMatch { pattern, then_case, else_case } => {
-            walk_pattern(v, pattern);
-            walk_block(v, then_case);
-            if let Some(block) = else_case.as_ref() {
-                walk_block(v, block)
-            }
-        }
-        CondList(arms) =>
-            for arm in arms {
-                match arm.condition {
-                    Condition::Pattern(ref pat) => {
-                        walk_pattern(v, pat);
-                    }
-                    Condition::TruncatedOp(ref _binop, ref expr) => {
-                        walk_expression(v, expr);
-                    }
-                    Condition::Else => (),
-                }
-                if let Some(ref guard) = arm.guard {
-                    walk_expression(v, guard);
-                }
-                walk_block(v, &arm.body);
-            },
-    }
-}
-
-pub fn walk_pattern<V: ASTVisitor>(v: &mut V, pat: &Pattern) {
-    use Pattern::*;
-
-    if let Recursion::Continue = v.pattern(pat) {
-        match pat {
-            TuplePattern(patterns) =>
-                for pat in patterns {
-                    walk_pattern(v, pat);
-                },
-            TupleStruct(_, patterns) =>
-                for pat in patterns {
-                    walk_pattern(v, pat);
-                },
-            Record(_, name_and_patterns) =>
-                for (_, pat) in name_and_patterns {
-                    walk_pattern(v, pat);
-                },
-            _ => (),
-        };
-    }
-}
--- a/schala-lang/src/ast/visualize.rs
+++ b/schala-lang/src/ast/visualize.rs
@ -1,282 +0,0 @@
-#![allow(clippy::single_char_add_str)]
-use std::fmt::Write;
-
-use super::{
-    Block, Declaration, Expression, ExpressionKind, FlowControl, ImportSpecifier, InvocationArgument,
-    Signature, Statement, StatementKind, AST,
-};
-
-const LEVEL: usize = 2;
-
-fn do_indent(n: usize, buf: &mut String) {
-    for _ in 0..n {
-        buf.push(' ');
-    }
-}
-
-fn newline(buf: &mut String) {
-    buf.push('\n');
-}
-
-pub(super) fn render_ast(ast: &AST) -> String {
-    let AST { statements, .. } = ast;
-
-    let mut buf = "(AST\n".to_string();
-    render_block(statements, LEVEL, &mut buf);
-
-    buf.push(')');
-
-    buf
-}
-
-fn render_statement(stmt: &Statement<StatementKind>, indent: usize, buf: &mut String) {
-    use StatementKind::*;
-    do_indent(indent, buf);
-    match stmt.kind {
-        Expression(ref expr) => render_expression(expr, indent, buf),
-        Declaration(ref decl) => render_declaration(decl, indent, buf),
-        Import(ref spec) => render_import(spec, indent, buf),
-        Flow(ref flow_control) => render_flow_control(flow_control, indent, buf),
-    }
-}
-
-fn render_expression(expr: &Expression, indent: usize, buf: &mut String) {
-    use ExpressionKind::*;
-
-    buf.push_str("(Expr ");
-    match &expr.kind {
-        SelfValue => write!(buf, "(SelfValue)").unwrap(),
-        NatLiteral(n) => buf.push_str(&format!("(NatLiteral {})", n)),
-        FloatLiteral(f) => buf.push_str(&format!("(FloatLiteral {})", f)),
-        StringLiteral { s, prefix } => buf.push_str(&format!("(StringLiteral prefix: {:?} {})", prefix, s)),
-        BoolLiteral(b) => buf.push_str(&format!("(BoolLiteral {})", b)),
-        BinExp(binop, lhs, rhs) => {
-            let new_indent = indent + LEVEL;
-            buf.push_str(&format!("Binop {}\n", binop.sigil()));
-
-            do_indent(new_indent, buf);
-            render_expression(lhs, new_indent, buf);
-            newline(buf);
-
-            do_indent(new_indent, buf);
-            render_expression(rhs, new_indent, buf);
-            newline(buf);
-
-            do_indent(indent, buf);
-        }
-        PrefixExp(prefix, expr) => {
-            let new_indent = indent + LEVEL;
-            buf.push_str(&format!("PrefixOp {}\n", prefix.sigil()));
-
-            do_indent(new_indent, buf);
-            render_expression(expr, new_indent, buf);
-            newline(buf);
-
-            do_indent(indent, buf);
-        }
-        TupleLiteral(..) => (),
-        Value(name) => {
-            buf.push_str(&format!("Value {})", name));
-        }
-        NamedStruct { name: _, fields: _ } => (),
-        Call { f, arguments } => {
-            let new_indent = indent + LEVEL;
-            buf.push_str("Call ");
-            render_expression(f, new_indent, buf);
-            newline(buf);
-
-            for arg in arguments {
-                do_indent(new_indent, buf);
-                match arg {
-                    InvocationArgument::Positional(expr) => render_expression(expr, new_indent, buf),
-                    InvocationArgument::Keyword { .. } => buf.push_str("<keyword>"),
-                    InvocationArgument::Ignored => buf.push_str("<ignored>"),
-                }
-                newline(buf);
-                do_indent(indent, buf);
-            }
-        }
-        Index { .. } => buf.push_str("<index>"),
-        IfExpression { .. } => buf.push_str("<if-expr>"),
-        WhileExpression { .. } => buf.push_str("<while-expr>"),
-        ForExpression { .. } => buf.push_str("<for-expr>"),
-        Lambda { params, type_anno: _, body } => {
-            let new_indent = indent + LEVEL;
-            buf.push_str("Lambda ");
-            newline(buf);
-
-            do_indent(new_indent, buf);
-            buf.push_str("(Args ");
-            for p in params {
-                buf.push_str(&format!("{} ", p.name));
-            }
-            buf.push(')');
-            newline(buf);
-
-            do_indent(new_indent, buf);
-            buf.push_str("(Body ");
-            newline(buf);
-            render_block(body, new_indent + LEVEL, buf);
-            do_indent(new_indent, buf);
-            buf.push(')');
-
-            newline(buf);
-            do_indent(indent, buf);
-        }
-        Access { .. } => buf.push_str("<access-expr>"),
-        ListLiteral(..) => buf.push_str("<list-literal>"),
-    }
-    buf.push(')');
-}
-fn render_declaration(decl: &Declaration, indent: usize, buf: &mut String) {
-    use Declaration::*;
-
-    buf.push_str("(Decl ");
-    match decl {
-        FuncSig(ref sig) => render_signature(sig, indent, buf),
-        FuncDecl(ref sig, ref block) => {
-            let indent = indent + LEVEL;
-            buf.push_str("Function");
-            newline(buf);
-
-            do_indent(indent, buf);
-            render_signature(sig, indent, buf);
-            newline(buf);
-
-            do_indent(indent, buf);
-            buf.push_str("(Body");
-            newline(buf);
-
-            render_block(block, indent + LEVEL, buf);
-            do_indent(indent, buf);
-            buf.push_str(")");
-            newline(buf);
-        }
-        TypeDecl { name: _, body: _, .. } => {
-            buf.push_str("<type-decl>");
-        }
-        TypeAlias { alias: _, original: _ } => {
-            buf.push_str("<type-alias>");
-        }
-        Binding { name, constant: _, type_anno: _, expr } => {
-            let new_indent = indent + LEVEL;
-            buf.push_str(&format!("Binding {}", name));
-            newline(buf);
-            do_indent(new_indent, buf);
-            render_expression(expr, new_indent, buf);
-            newline(buf);
-        }
-        Module { name, items: _ } => {
-            write!(buf, "(Module {} <body>)", name).unwrap();
-        }
-        _ => (), /*
-                 Impl { type_name: TypeIdentifier, interface_name: Option<TypeSingletonName>, block: Vec<Declaration> },
-                 Interface { name: Rc<String>, signatures: Vec<Signature> },
-                 Annotation { name: Rc<String>, arguments: Vec<Expression> },
-                     */
-    }
-    do_indent(indent, buf);
-    buf.push(')');
-}
-
-fn render_block(block: &Block, indent: usize, buf: &mut String) {
-    for stmt in block.statements.iter() {
-        render_statement(stmt, indent, buf);
-        newline(buf);
-    }
-}
-
-fn render_signature(sig: &Signature, _indent: usize, buf: &mut String) {
-    buf.push_str(&format!("(Signature {} )", sig.name));
-}
-
-fn render_import(_import: &ImportSpecifier, _indent: usize, buf: &mut String) {
-    buf.push_str("(Import <some import>)");
-}
-
-fn render_flow_control(flow: &FlowControl, _indent: usize, buf: &mut String) {
-    use FlowControl::*;
-    match flow {
-        Return(ref _expr) => write!(buf, "return <expr>").unwrap(),
-        Break => write!(buf, "break").unwrap(),
-        Continue => write!(buf, "continue").unwrap(),
-    }
-}
-
-#[cfg(test)]
-mod test {
-    use super::render_ast;
-    use crate::util::quick_ast;
-
-    #[test]
-    fn test_visualization() {
-        let ast = quick_ast(
-            r#"
-    fn test(x) {
-        let m = 9
-        1 * 4 <> m |> somemod::output(x)
-    }
-
-    let quincy = \(no, yes, maybe) {
-        let a = 10
-        yes * no + a
-    }
-
-    let b = 54
-    test(b) == 3
-    "#,
-        );
-
-        let expected_output = r#"(AST
-  (Decl Function
-    (Signature test )
-    (Body
-      (Decl Binding m
-        (Expr (NatLiteral 9))
-      )
-      (Expr Binop *
-        (Expr (NatLiteral 1))
-        (Expr Binop |>
-          (Expr Binop <>
-            (Expr (NatLiteral 4))
-            (Expr Value m))
-          )
-          (Expr Call (Expr Value somemod::output))
-            (Expr Value x))
-          )
-        )
-      )
-    )
-  )
-  (Decl Binding quincy
-    (Expr Lambda 
-      (Args no yes maybe )
-      (Body 
-        (Decl Binding a
-          (Expr (NatLiteral 10))
-        )
-        (Expr Binop +
-          (Expr Binop *
-            (Expr Value yes))
-            (Expr Value no))
-          )
-          (Expr Value a))
-        )
-      )
-    )
-  )
-  (Decl Binding b
-    (Expr (NatLiteral 54))
-  )
-  (Expr Binop ==
-    (Expr Call (Expr Value test))
-      (Expr Value b))
-    )
-    (Expr (NatLiteral 3))
-  )
-)"#;
-
-        let rendered = render_ast(&ast);
-        assert_eq!(rendered, expected_output);
-    }
-}
--- a/schala-lang/src/builtin.rs
+++ b/schala-lang/src/builtin.rs
@ -1,130 +0,0 @@
-use std::{convert::TryFrom, str::FromStr};
-
-use crate::{
-    ast::{BinOp, PrefixOp},
-    type_inference::Type,
-};
-
-/// "Builtin" computational operations with some kind of semantics, mostly mathematical operations.
-#[derive(Debug, Clone, Copy, PartialEq)]
-pub enum Builtin {
-    Add,
-    Increment,
-    Subtract,
-    Negate,
-    Multiply,
-    Divide,
-    Quotient,
-    Modulo,
-    Exponentiation,
-    BitwiseAnd,
-    BitwiseOr,
-    BooleanAnd,
-    BooleanOr,
-    BooleanNot,
-    Equality,
-    LessThan,
-    LessThanOrEqual,
-    GreaterThan,
-    GreaterThanOrEqual,
-    Comparison,
-    IOPrint,
-    IOPrintLn,
-    IOGetLine,
-    Assignment,
-    Concatenate,
-    NotEqual,
-}
-
-impl Builtin {
-    #[allow(dead_code)]
-    pub fn get_type(&self) -> Type {
-        use Builtin::*;
-        match self {
-            Add => ty!(Nat -> Nat -> Nat),
-            Subtract => ty!(Nat -> Nat -> Nat),
-            Multiply => ty!(Nat -> Nat -> Nat),
-            Divide => ty!(Nat -> Nat -> Float),
-            Quotient => ty!(Nat -> Nat -> Nat),
-            Modulo => ty!(Nat -> Nat -> Nat),
-            Exponentiation => ty!(Nat -> Nat -> Nat),
-            BitwiseAnd => ty!(Nat -> Nat -> Nat),
-            BitwiseOr => ty!(Nat -> Nat -> Nat),
-            BooleanAnd => ty!(Bool -> Bool -> Bool),
-            BooleanOr => ty!(Bool -> Bool -> Bool),
-            BooleanNot => ty!(Bool -> Bool),
-            Equality => ty!(Nat -> Nat -> Bool),
-            LessThan => ty!(Nat -> Nat -> Bool),
-            LessThanOrEqual => ty!(Nat -> Nat -> Bool),
-            GreaterThan => ty!(Nat -> Nat -> Bool),
-            GreaterThanOrEqual => ty!(Nat -> Nat -> Bool),
-            Comparison => ty!(Nat -> Nat -> Ordering),
-            IOPrint => ty!(Unit),
-            IOPrintLn => ty!(Unit),
-            IOGetLine => ty!(StringT),
-            Assignment => ty!(Unit),
-            Concatenate => ty!(StringT -> StringT -> StringT),
-            Increment => ty!(Nat -> Int),
-            Negate => ty!(Nat -> Int),
-            NotEqual => ty!(Nat -> Nat -> Bool),
-        }
-    }
-}
-
-impl TryFrom<&BinOp> for Builtin {
-    type Error = ();
-
-    fn try_from(binop: &BinOp) -> Result<Self, Self::Error> {
-        FromStr::from_str(binop.sigil())
-    }
-}
-
-impl TryFrom<&PrefixOp> for Builtin {
-    type Error = ();
-
-    fn try_from(prefix_op: &PrefixOp) -> Result<Self, Self::Error> {
-        use Builtin::*;
-
-        match prefix_op.sigil() {
-            "+" => Ok(Increment),
-            "-" => Ok(Negate),
-            "!" => Ok(BooleanNot),
-            _ => Err(()),
-        }
-    }
-}
-
-impl FromStr for Builtin {
-    type Err = ();
-
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        use Builtin::*;
-        Ok(match s {
-            "+" => Add,
-            "-" => Subtract,
-            "*" => Multiply,
-            "/" => Divide,
-            "quot" => Quotient,
-            "%" => Modulo,
-            "++" => Concatenate,
-            "^" => Exponentiation,
-            "&" => BitwiseAnd,
-            "&&" => BooleanAnd,
-            "|" => BitwiseOr,
-            "||" => BooleanOr,
-            "!" => BooleanNot,
-            ">" => GreaterThan,
-            ">=" => GreaterThanOrEqual,
-            "<" => LessThan,
-            "<=" => LessThanOrEqual,
-            "==" => Equality,
-            "!=" => NotEqual,
-            "=" => Assignment,
-            "<=>" => Comparison,
-            "print" => IOPrint,
-            "println" => IOPrintLn,
-            "getline" => IOGetLine,
-            _ => return Err(()),
-        })
-    }
-}
--- a/schala-lang/src/error.rs
+++ b/schala-lang/src/error.rs
@ -1,79 +0,0 @@
-use crate::{
-    parsing::{Location, ParseError},
-    schala::{SourceReference, Stage},
-    symbol_table::SymbolError,
-    type_inference::TypeError,
-};
-
-pub struct SchalaError {
-    errors: Vec<Error>,
-}
-
-impl SchalaError {
-    pub(crate) fn display(&self) -> String {
-        match self.errors[0] {
-            Error::Parse(ref parse_err) => parse_err.to_string(),
-            Error::Standard { ref text, .. } => text.as_ref().cloned().unwrap_or_default(),
-        }
-    }
-
-    #[allow(dead_code)]
-    pub(crate) fn from_type_error(err: TypeError) -> Self {
-        Self {
-            errors: vec![Error::Standard { location: None, text: Some(err.msg), stage: Stage::Typechecking }],
-        }
-    }
-
-    pub(crate) fn from_symbol_table(symbol_errs: Vec<SymbolError>) -> Self {
-        //TODO this could be better
-        let errors = symbol_errs
-            .into_iter()
-            .map(|_symbol_err| Error::Standard {
-                location: None,
-                text: Some("symbol table error".to_string()),
-                stage: Stage::Symbols,
-            })
-            .collect();
-        Self { errors }
-    }
-
-    pub(crate) fn from_string(text: String, stage: Stage) -> Self {
-        Self { errors: vec![Error::Standard { location: None, text: Some(text), stage }] }
-    }
-
-    pub(crate) fn from_parse_error(parse_error: ParseError, source_reference: &SourceReference) -> Self {
-        let formatted_parse_error = format_parse_error(parse_error, source_reference);
-        Self { errors: vec![Error::Parse(formatted_parse_error)] }
-    }
-}
-
-#[allow(dead_code)]
-enum Error {
-    Standard { location: Option<Location>, text: Option<String>, stage: Stage },
-    Parse(String),
-}
-
-fn format_parse_error(error: ParseError, source_reference: &SourceReference) -> String {
-    let offset = error.location.offset;
-    let (line_start, line_num, line_from_program) = source_reference.get_line(offset);
-    let ch = offset - line_start;
-
-    let location_pointer = format!("{}^", " ".repeat(ch));
-
-    let line_num_digits = format!("{}", line_num).chars().count();
-    let space_padding = " ".repeat(line_num_digits);
-
-    format!(
-        r#"
-{error_msg}
-{space_padding} |
-{line_num} | {}
-{space_padding} | {}
-"#,
-        line_from_program,
-        location_pointer,
-        error_msg = error.msg,
-        space_padding = space_padding,
-        line_num = line_num,
-    )
-}
--- a/schala-lang/src/identifier.rs
+++ b/schala-lang/src/identifier.rs
@ -1,75 +0,0 @@
-use std::{
-    fmt::{self, Debug},
-    hash::Hash,
-    marker::PhantomData,
-};
-
-pub trait IdKind: Debug + Copy + Clone + Hash + PartialEq + Eq + Default {
-    fn tag() -> &'static str;
-}
-
-/// A generalized abstract identifier type of up to 2^32-1 entries.
-#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq, Default)]
-pub struct Id<T>
-where T: IdKind
-{
-    idx: u32,
-    t: PhantomData<T>,
-}
-
-impl<T> Id<T>
-where T: IdKind
-{
-    fn new(n: u32) -> Self {
-        Self { idx: n, t: PhantomData }
-    }
-
-    #[allow(dead_code)]
-    pub fn as_u32(&self) -> u32 {
-        self.idx
-    }
-}
-
-impl<T> fmt::Display for Id<T>
-where T: IdKind
-{
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}:{}", self.idx, T::tag())
-    }
-}
-
-#[derive(Debug)]
-pub struct IdStore<T>
-where T: IdKind
-{
-    last_idx: u32,
-    t: PhantomData<T>,
-}
-
-impl<T> IdStore<T>
-where T: IdKind
-{
-    pub fn new() -> Self {
-        Self { last_idx: 0, t: PhantomData }
-    }
-
-    pub fn fresh(&mut self) -> Id<T> {
-        let idx = self.last_idx;
-        self.last_idx += 1;
-        Id::new(idx)
-    }
-}
-
-macro_rules! define_id_kind {
-    ($name:ident) => {
-        #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq, Default)]
-        pub struct $name;
-        impl crate::identifier::IdKind for $name {
-            fn tag() -> &'static str {
-                stringify!($name)
-            }
-        }
-    };
-}
-
-pub(crate) use define_id_kind;
--- a/schala-lang/src/parsing/combinator.rs
+++ b/schala-lang/src/parsing/combinator.rs
--- a/schala-lang/src/parsing/mod.rs
+++ b/schala-lang/src/parsing/mod.rs
@ -1,126 +0,0 @@
-#![allow(clippy::upper_case_acronyms)]
-
-pub mod combinator;
-mod peg_parser;
-mod test;
-
-use std::{cell::RefCell, fmt, rc::Rc};
-
-use combinator::Span;
-
-#[cfg(test)]
-use crate::ast::{Block, Expression};
-use crate::{
-    ast::{ASTItem, AST},
-    identifier::{Id, IdStore},
-};
-
-pub(crate) type StoreRef = Rc<RefCell<IdStore<ASTItem>>>;
-pub struct Parser {
-    id_store: StoreRef,
-    use_combinator: bool,
-}
-
-impl Parser {
-    pub(crate) fn new() -> Self {
-        let id_store: IdStore<ASTItem> = IdStore::new();
-        Self { id_store: Rc::new(RefCell::new(id_store)), use_combinator: true }
-    }
-    pub(crate) fn parse(&mut self, input: &str) -> Result<AST, ParseError> {
-        if self.use_combinator {
-            self.parse_comb(input)
-        } else {
-            self.parse_peg(input)
-        }
-    }
-
-    pub(crate) fn parse_peg(&mut self, input: &str) -> Result<AST, ParseError> {
-        peg_parser::schala_parser::program(input, self).map_err(ParseError::from_peg)
-    }
-
-    pub(crate) fn parse_comb(&mut self, input: &str) -> Result<AST, ParseError> {
-        let span = Span::new_extra(input, self.id_store.clone());
-        convert(input, combinator::program(span))
-    }
-
-    #[cfg(test)]
-    fn expression(&mut self, input: &str) -> Result<Expression, ParseError> {
-        peg_parser::schala_parser::expression(input, self).map_err(ParseError::from_peg)
-    }
-
-    #[cfg(test)]
-    fn expression_comb(&mut self, input: &str) -> Result<Expression, ParseError> {
-        let span = Span::new_extra(input, self.id_store.clone());
-        convert(input, combinator::expression(span))
-    }
-
-    #[cfg(test)]
-    fn block(&mut self, input: &str) -> Result<Block, ParseError> {
-        peg_parser::schala_parser::block(input, self).map_err(ParseError::from_peg)
-    }
-
-    #[cfg(test)]
-    fn block_comb(&mut self, input: &str) -> Result<Block, ParseError> {
-        let span = Span::new_extra(input, self.id_store.clone());
-        convert(input, combinator::block(span))
-    }
-
-    fn fresh(&mut self) -> Id<ASTItem> {
-        self.id_store.borrow_mut().fresh()
-    }
-}
-
-fn convert<'a, O>(input: &'a str, result: combinator::ParseResult<'a, O>) -> Result<O, ParseError> {
-    use nom::{error::VerboseError, Finish};
-
-    match result.finish() {
-        Ok((rest, output)) => {
-            if rest.fragment() != &"" {
-                return Err(ParseError {
-                    location: Default::default(),
-                    msg: format!("Bad parse state, remaining text: `{}`", rest.fragment()),
-                });
-            }
-
-            Ok(output)
-        }
-        Err(err) => {
-            let err = VerboseError {
-                errors: err.errors.into_iter().map(|(sp, kind)| (*sp.fragment(), kind)).collect(),
-            };
-            let msg = nom::error::convert_error(input, err);
-            Err(ParseError { msg, location: (0).into() })
-        }
-    }
-}
-
-/// Represents a parsing error
-#[derive(Debug)]
-pub struct ParseError {
-    pub msg: String,
-    pub location: Location,
-}
-
-impl ParseError {
-    fn from_peg(err: peg::error::ParseError<peg::str::LineCol>) -> Self {
-        let msg = err.to_string();
-        Self { msg, location: err.location.offset.into() }
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Default)]
-pub struct Location {
-    pub(crate) offset: usize,
-}
-
-impl From<usize> for Location {
-    fn from(offset: usize) -> Self {
-        Self { offset }
-    }
-}
-
-impl fmt::Display for Location {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}", self.offset)
-    }
-}
--- a/schala-lang/src/parsing/peg_parser.rs
+++ b/schala-lang/src/parsing/peg_parser.rs
@ -1,567 +0,0 @@
-use std::rc::Rc;
-
-use super::Parser;
-use crate::ast::*;
-
-fn rc_string(s: &str) -> Rc<String> {
-    Rc::new(s.to_string())
-}
-
-enum ExtendedPart<'a> {
-    Index(Vec<Expression>),
-    Accessor(&'a str),
-    Call(Vec<InvocationArgument>),
-}
-
-peg::parser! {
-    pub grammar schala_parser() for str {
-
-        rule whitespace() = [' ' | '\t' ]
-        rule whitespace_or_newline() = [' ' | '\t' | '\n' ]
-
-        rule _ = quiet!{ (block_comment() / line_comment() / whitespace())* }
-
-        rule __ = quiet!{ (block_comment() / line_comment() / whitespace_or_newline())* }
-
-        rule block_comment() = "/*" (block_comment() / !"*/" [_])* "*/"
-        rule line_comment() = "//" (!['\n'] [_])* &"\n"
-
-
-        pub rule program(parser: &mut Parser) -> AST =
-            __ statements:(statement(parser) ** (delimiter()+) ) __ { AST { id: parser.fresh(), statements: statements.into() } }
-
-        rule delimiter() = (";" / "\n")+
-
-        //Note - this is a hack, ideally the rule `rule block() -> Block = "{" _ items:(statement() **
-        //delimiter()) _ "}" { items.into() }` would've worked, but it doesn't.
-        pub rule block(parser: &mut Parser) -> Block =
-            "{" __ items:(statement(parser) ** delimiter()) delimiter()? __ "}" { items.into() } /
-            "{" __ stmt:statement(parser) __ "}" { vec![stmt].into() }
-
-        rule block_item(parser: &mut Parser) -> Statement<StatementKind> =
-            _ stmt:statement(parser) _ delimiter()+ { stmt }
-
-        rule statement(parser: &mut Parser) -> Statement<StatementKind> =
-             _ pos:position!() kind:statement_kind(parser) _ { Statement { id: parser.fresh(), location: pos.into(), kind } }
-
-        rule statement_kind(parser: &mut Parser) -> StatementKind =
-            __ import:import(parser) { StatementKind::Import(import) } /
-            __ decl:declaration(parser) { StatementKind::Declaration(decl) } /
-            __ flow:flow(parser) { StatementKind::Flow(flow) } /
-            __ expr:expression(parser) { StatementKind::Expression(expr) }
-
-        rule flow(parser: &mut Parser) -> FlowControl =
-            "continue" { FlowControl::Continue } /
-            "break" { FlowControl::Break } /
-            "return" _ expr:expression(parser)? { FlowControl::Return(expr) }
-
-            //TODO add the ability to rename and exclude imports
-        rule import(parser: &mut Parser) -> ImportSpecifier =
-            "import" _ path_components:path_components() suffix:import_suffix()? {
-                ImportSpecifier {
-                    id: parser.fresh(),
-                    path_components,
-                    imported_names: suffix.unwrap_or(ImportedNames::LastOfPath)
-                }
-            }
-
-        rule path_components() -> Vec<Rc<String>> =
-            "::"? name:identifier() rest:path_component()* {
-                let mut items = vec![rc_string(name)];
-                items.extend(rest.into_iter().map(rc_string));
-                items
-            }
-
-        rule path_component() -> &'input str = "::" ident:identifier() { ident }
-
-        rule import_suffix() -> ImportedNames =
-            "::*" { ImportedNames::All } /
-            "::{" __ names:(identifier() ** (_ "," _)) __ "}" {?
-                if names.is_empty() {
-                    Err("import groups must have at least one item")
-                } else {
-                    Ok(ImportedNames::List(names.into_iter().map(rc_string).collect()))
-                }
-            }
-
-        rule declaration(parser: &mut Parser) -> Declaration =
-            binding(parser) / type_decl(parser) / annotation(parser) / func(parser) / interface(parser) /
-            implementation(parser) / module(parser)
-
-        rule module(parser: &mut Parser) -> Declaration =
-            "module" _ name:identifier() _ items:block(parser) { Declaration::Module { name: rc_string(name), items } }
-
-        rule implementation(parser: &mut Parser) -> Declaration =
-            "impl" _ interface:type_singleton_name() _ "for" _ type_name:type_identifier() _ block:decl_block(parser) {
-                Declaration::Impl { type_name, interface_name: Some(interface), block }
-
-            } /
-            "impl" _ type_name:type_identifier() _ block:decl_block(parser) {
-                Declaration::Impl { type_name, interface_name: None, block }
-            }
-
-        rule decl_block(parser: &mut Parser) -> Vec<Statement<Declaration>> =
-            "{" __ decls:(func_declaration_stmt(parser) ** (delimiter()+)) delimiter()? __ "}" { decls }
-
-        rule func_declaration_stmt(parser: &mut Parser) -> Statement<Declaration> =
-            pos:position!() decl:func_declaration(parser) { Statement { id: parser.fresh(), location: pos.into(), kind: decl } }
-
-        rule interface(parser: &mut Parser) -> Declaration =
-            "interface" _ name:identifier() _ signatures:signature_block(parser) { Declaration::Interface { name: rc_string(name), signatures } }
-
-        rule signature_block(parser: &mut Parser) -> Vec<Signature> =
-            "{" __  signatures:(func_signature(parser) ** (delimiter()+)) __ "}" { signatures }
-
-        rule func(parser: &mut Parser) -> Declaration =
-            decl:func_declaration(parser) { decl } /
-            sig:func_signature(parser) { Declaration::FuncSig(sig) }
-
-        rule func_declaration(parser: &mut Parser) -> Declaration =
-            _ sig:func_signature(parser) __ body:block(parser) { Declaration::FuncDecl(sig, body) }
-
-        rule func_signature(parser: &mut Parser) -> Signature =
-            _ "fn" _ name:identifier() "(" _ params:formal_params(parser) _ ")" _ type_anno:type_anno()? { Signature {
-                name: rc_string(name), operator: false, params, type_anno
-            } } /
-            _ "fn" _ "(" op:operator() ")" _ "(" _ params:formal_params(parser) _ ")" _ type_anno:type_anno()? { Signature {
-                name: rc_string(op), operator: true, params, type_anno
-            } }
-
-        rule formal_params(parser: &mut Parser) -> Vec<FormalParam> =
-            params:(formal_param(parser) ** (_ "," _)) {? if params.len() < 256 { Ok(params) } else {
-            Err("function-too-long") }
-            }
-
-        rule formal_param(parser: &mut Parser) -> FormalParam =
-            name:identifier() _ anno:type_anno()? _ "=" expr:expression(parser) { FormalParam { name: rc_string(name),
-               default: Some(expr), anno } } /
-            name:identifier() _ anno:type_anno()? { FormalParam { name: rc_string(name), default: None, anno } }
-
-
-        rule annotation(parser: &mut Parser) -> Declaration =
-            "@" name:identifier() args:annotation_args(parser)? delimiter()+ _ inner:statement(parser) { Declaration::Annotation {
-                name: rc_string(name), arguments: if let Some(args) = args { args } else { vec![] }, inner: Box::new(inner) }
-            }
-
-        rule annotation_args(parser: &mut Parser) -> Vec<Expression> =
-            "(" _ args:(expression(parser) ** (_ "," _)) _ ")" { args }
-
-
-        rule binding(parser: &mut Parser) -> Declaration =
-            "let" _ mutable:"mut"? _ ident:identifier() _ type_anno:type_anno()? _ "=" _ expr:expression(parser) {
-                Declaration::Binding { name: Rc::new(ident.to_string()), constant: mutable.is_none(),
-                type_anno, expr }
-            }
-
-
-        rule type_decl(parser: &mut Parser) -> Declaration =
-            "type" _ "alias" _ alias:type_alias() { alias } /
-            "type" _ mutable:"mut"? _ name:type_singleton_name() _ "=" _ body:type_body(parser) {
-                Declaration::TypeDecl { name, body, mutable: mutable.is_some() }
-            }
-
-        rule type_singleton_name() -> TypeSingletonName =
-            name:identifier() params:type_params()? { TypeSingletonName {
-                name: rc_string(name), params: if let Some(params) = params { params } else { vec![] }
-            } }
-
-        rule type_params() -> Vec<TypeIdentifier> =
-            "<" _ idents:(type_identifier() ** (_ "," _)) _ ">" { idents }
-
-        rule type_identifier() -> TypeIdentifier =
-            "(" _ items:(type_identifier() ** (_ "," _)) _ ")" { TypeIdentifier::Tuple(items) } /
-            singleton:type_singleton_name() { TypeIdentifier::Singleton(singleton) }
-
-        rule type_body(parser: &mut Parser) -> TypeBody =
-            "{" _ items:(record_variant_item() ** (__ "," __)) __ "}" { TypeBody::ImmediateRecord { id: parser.fresh(), fields: items } } /
-            variants:(variant_spec(parser) ** (__ "|" __)) { TypeBody::Variants(variants) }
-
-        rule variant_spec(parser: &mut Parser) -> Variant =
-            name:identifier() __ "{" __ typed_identifier_list:(record_variant_item() ** (__ "," __)) __ ","? __ "}" { Variant {
-                id: parser.fresh(), name: rc_string(name), kind: VariantKind::Record(typed_identifier_list)
-            } } /
-            name:identifier() "(" tuple_members:(type_identifier() ++ (__ "," __)) ")" { Variant {
-                id: parser.fresh(), name: rc_string(name), kind: VariantKind::TupleStruct(tuple_members) } } /
-            name:identifier() { Variant { id: parser.fresh(), name: rc_string(name), kind: VariantKind::UnitStruct } }
-
-        rule record_variant_item() -> (Rc<String>, TypeIdentifier) =
-            name:identifier() _ ":" _ ty:type_identifier() { (rc_string(name), ty) }
-
-        rule type_alias() -> Declaration =
-            alias:identifier() _ "=" _ name:identifier() { Declaration::TypeAlias { alias: rc_string(alias), original: rc_string(name), } }
-
-        rule type_anno() -> TypeIdentifier =
-            ":" _ identifier:type_identifier() { identifier }
-
-        pub rule expression(parser: &mut Parser) -> Expression =
-            __ kind:expression_kind(true, parser) _ type_anno:type_anno()? { Expression { id: parser.fresh(), type_anno, kind } }
-
-        rule expression_no_struct(parser: &mut Parser) -> Expression =
-            __ kind:expression_kind(false, parser) { Expression { id: parser.fresh(), type_anno: None, kind } }
-
-        rule expression_kind(struct_ok: bool, parser: &mut Parser) -> ExpressionKind =
-            precedence_expr(struct_ok, parser)
-
-        rule precedence_expr(struct_ok: bool, parser: &mut Parser) -> ExpressionKind =
-        first:prefix_expr(struct_ok, parser) _ next:(precedence_continuation(struct_ok, parser))* {
-            let next = next.into_iter().map(|(sigil, expr)| (BinOp::from_sigil(sigil), expr)).collect();
-            BinopSequence { first, next }.do_precedence(parser)
-        }
-
-        rule precedence_continuation(struct_ok: bool, parser: &mut Parser) -> (&'input str, ExpressionKind) =
-            op:operator() _ expr:prefix_expr(struct_ok, parser) _ { (op, expr) }
-
-        rule prefix_expr(struct_ok: bool, parser: &mut Parser) -> ExpressionKind =
-            prefix:prefix()? expr:extended_expr(struct_ok, parser) {
-                if let Some(p) = prefix {
-                    let expr = Expression::new(parser.fresh(), expr);
-                    let prefix = PrefixOp::from_sigil(p);
-                    ExpressionKind::PrefixExp(prefix, Box::new(expr))
-                } else {
-                    expr
-                }
-            }
-
-
-        rule prefix() -> &'input str =
-            $(['+' | '-' | '!' ])
-
-        //TODO make the definition of operators more complex
-        rule operator() -> &'input str =
-            quiet!{!"*/" s:$( ['+' | '-' | '*' | '/' | '%' | '<' | '>' | '=' | '!' | '$' | '&' | '|' | '?' | '^' | '`']+ ) { s } } /
-            expected!("operator")
-
-        rule extended_expr(struct_ok: bool, parser: &mut Parser) -> ExpressionKind =
-            primary:primary(struct_ok, parser) parts:(extended_expr_part(parser)*) {
-                let mut expression = Expression::new(parser.fresh(), primary);
-                for part in parts.into_iter() {
-                    let kind = match part {
-                        ExtendedPart::Index(indexers) => {
-                            ExpressionKind::Index { indexee: Box::new(expression), indexers }
-                        },
-                        ExtendedPart::Accessor(name) => {
-                            let name = rc_string(name);
-                            ExpressionKind::Access { name, expr: Box::new(expression) }
-                        },
-                        ExtendedPart::Call(arguments) => {
-                            ExpressionKind::Call { f: Box::new(expression), arguments }
-                        }
-                    };
-
-                    expression = Expression::new(parser.fresh(), kind);
-                }
-
-                expression.kind
-            }
-
-        rule extended_expr_part(parser: &mut Parser) -> ExtendedPart<'input> =
-            indexers:index_part(parser) { ExtendedPart::Index(indexers) } /
-            arguments:call_part(parser) { ExtendedPart::Call(arguments) } /
-            "." name:identifier() { ExtendedPart::Accessor(name) }
-
-        rule index_part(parser: &mut Parser) -> Vec<Expression> =
-            "[" indexers:(expression(parser) ++ ",") "]" { indexers }
-
-        rule call_part(parser: &mut Parser) -> Vec<InvocationArgument> =
-            "(" arguments:(invocation_argument(parser) ** ",") ")" { arguments }
-
-        rule invocation_argument(parser: &mut Parser) -> InvocationArgument =
-            _ "_" _ { InvocationArgument::Ignored } /
-            _ ident:identifier() _ "=" _ expr:expression(parser) { InvocationArgument::Keyword {
-                name: Rc::new(ident.to_string()),
-                expr
-                } } /
-            _ expr:expression(parser) _ { InvocationArgument::Positional(expr) }
-
-
-        rule primary(struct_ok: bool, parser: &mut Parser) -> ExpressionKind =
-            while_expr(parser) / for_expr(parser) / float_literal() / nat_literal() / bool_literal() /
-            string_literal() / paren_expr(parser) /
-            list_expr(parser) / if_expr(parser) / lambda_expr(parser) /
-            item:named_struct(parser) {? if struct_ok { Ok(item) } else { Err("no-struct-allowed") } } /
-            identifier_expr(parser)
-
-        rule lambda_expr(parser: &mut Parser) -> ExpressionKind =
-            r#"\"# __ "(" _ params:formal_params(parser) _ ")" _ type_anno:(type_anno()?) _ body:block(parser)  {
-                ExpressionKind::Lambda { params, type_anno, body }
-            } /
-            r#"\"# param:formal_param(parser) _ type_anno:(type_anno()?) _ body:block(parser) {
-                ExpressionKind::Lambda { params: vec![param], type_anno, body }
-            }
-
-        rule for_expr(parser: &mut Parser) -> ExpressionKind =
-            "for" _ enumerators:for_enumerators(parser) _ body:for_body(parser) {
-                ExpressionKind::ForExpression { enumerators, body }
-            }
-
-        rule for_enumerators(parser: &mut Parser) -> Vec<Enumerator> =
-            "{" _ enumerators:(enumerator(parser) ++ ",") _ "}" { enumerators } /
-            enumerator:enumerator(parser) { vec![enumerator] }
-
-        //TODO add guards, etc.
-        rule enumerator(parser: &mut Parser) -> Enumerator =
-            ident:identifier() _ "<-" _ generator:expression_no_struct(parser) {
-                Enumerator { identifier: Rc::new(ident.to_string()), generator, assignment: false }
-            } /
-            //TODO need to distinguish these two cases in AST
-            ident:identifier() _ "=" _ generator:expression_no_struct(parser) {
-                Enumerator { identifier: Rc::new(ident.to_string()), generator, assignment: true }
-            }
-
-        rule for_body(parser: &mut Parser) -> Box<ForBody> =
-            "return" _ expr:expression(parser) { Box::new(ForBody::MonadicReturn(expr)) } /
-            body:block(parser) { Box::new(ForBody::StatementBlock(body)) }
-
-        rule while_expr(parser: &mut Parser) -> ExpressionKind =
-            "while" _ cond:expression_kind(false, parser)? _ body:block(parser) {
-                ExpressionKind::WhileExpression {
-                    condition: cond.map(|kind| Box::new(Expression::new(parser.fresh(), kind))),
-                    body,
-                }
-            }
-
-
-        rule identifier_expr(parser: &mut Parser) -> ExpressionKind =
-            qn:qualified_identifier(parser) { ExpressionKind::Value(qn) }
-
-        rule named_struct(parser: &mut Parser) -> ExpressionKind =
-            name:qualified_identifier(parser) _ fields:record_block(parser) {
-                ExpressionKind::NamedStruct {
-                    name,
-                    fields: fields.into_iter().map(|(n, exp)| (Rc::new(n.to_string()), exp)).collect(),
-                }
-            }
-
-
-        //TODO support anonymous structs and Elm-style update syntax for structs
-        rule record_block(parser: &mut Parser) -> Vec<(&'input str, Expression)> =
-            "{" _ entries:(record_entry(parser) ** ",") _ "}" { entries }
-
-        rule record_entry(parser: &mut Parser) -> (&'input str, Expression) =
-            _ name:identifier() _ ":" _ expr:expression(parser) _ { (name, expr) }
-
-        rule qualified_identifier(parser: &mut Parser) -> QualifiedName =
-            names:(identifier() ++ "::") { QualifiedName { id: parser.fresh(), components: names.into_iter().map(|name| Rc::new(name.to_string())).collect() } }
-
-        //TODO improve the definition of identifiers
-        rule identifier() -> &'input str =
-            !(reserved() !(ident_continuation())) text:$(['a'..='z' | 'A'..='Z' | '_'] ident_continuation()*) { text }
-
-        rule ident_continuation() -> &'input str =
-            text:$(['a'..='z' | 'A'..='Z' | '0'..='9' | '_'])
-
-        rule reserved() = "if" / "then" / "else" / "is" / "fn" / "for" / "while" / "let" / "in" / "mut" / "return" /
-            "break" / "alias" / "type" / "self" / "Self" / "interface" / "impl" / "true" / "false" / "module" / "import"
-
-
-        rule if_expr(parser: &mut Parser) -> ExpressionKind =
-            "if" _ discriminator:(expression(parser)?) _ body:if_expr_body(parser) {
-                ExpressionKind::IfExpression {
-                    discriminator: discriminator.map(Box::new),
-                    body: Box::new(body),
-                }
-            }
-
-        rule if_expr_body(parser: &mut Parser) -> IfExpressionBody =
-            cond_block(parser) / simple_pattern_match(parser) / simple_conditional(parser)
-
-        rule simple_conditional(parser: &mut Parser) -> IfExpressionBody =
-            "then" _ then_case:expr_or_block(parser) _ else_case:else_case(parser) {
-                IfExpressionBody::SimpleConditional { then_case, else_case }
-            }
-
-        rule simple_pattern_match(parser: &mut Parser) -> IfExpressionBody =
-            "is" _ pattern:pattern(parser) _ "then" _ then_case:expr_or_block(parser) _ else_case:else_case(parser) {
-                IfExpressionBody::SimplePatternMatch { pattern, then_case, else_case }
-            }
-
-        rule cond_block(parser: &mut Parser) -> IfExpressionBody =
-            "{" __ cond_arms:(cond_arm(parser) ++ (delimiter()+)) __ "}" { IfExpressionBody::CondList(cond_arms) }
-
-        rule cond_arm(parser: &mut Parser) -> ConditionArm =
-            _ "else" _ body:expr_or_block(parser) { ConditionArm { condition: Condition::Else, guard: None, body } } /
-            _ condition:condition(parser) _ guard:condition_guard(parser) _ "then" _ body:expr_or_block(parser)
-                { ConditionArm { condition, guard, body } }
-
-        rule condition(parser: &mut Parser) -> Condition =
-            "is" _ pat:pattern(parser) { Condition::Pattern(pat) } /
-            op:operator() _ expr:expression(parser) { Condition::TruncatedOp(BinOp::from_sigil(op), expr) }
-
-        rule condition_guard(parser: &mut Parser) -> Option<Expression> =
-            ("if" _ expr:expression(parser) { expr } )?
-
-        rule expr_or_block(parser: &mut Parser) -> Block = block(parser) / pos:position!() ex:expression(parser) {
-            Statement {
-                id: parser.fresh() , location: pos.into(),
-                kind: StatementKind::Expression(ex)
-            }.into()
-        }
-
-        rule else_case(parser: &mut Parser) -> Option<Block> =
-            ("else" _ eorb:expr_or_block(parser) { eorb })?
-
-        rule pattern(parser: &mut Parser) -> Pattern =
-            "(" _ variants:(pattern(parser) ++ ",") _ ")" { Pattern::TuplePattern(variants) } /
-            _ pat:simple_pattern(parser) { pat }
-
-        rule simple_pattern(parser: &mut Parser) -> Pattern =
-            pattern_literal() /
-            qn:qualified_identifier(parser) "(" members:(pattern(parser) ** ",") ")" {
-                Pattern::TupleStruct(qn, members)
-            } /
-            qn:qualified_identifier(parser) _ "{" _ items:(record_pattern_entry(parser) ** ",") "}" _ {
-                let items = items.into_iter().map(|(name, pat)| (Rc::new(name.to_string()), pat)).collect();
-                Pattern::Record(qn, items)
-            } /
-            qn:qualified_identifier(parser) { Pattern::VarOrName(qn) }
-
-        rule record_pattern_entry(parser: &mut Parser) -> (&'input str, Pattern) =
-            _ name:identifier() _ ":" _ pat:pattern(parser) _ { (name, pat) } /
-            _ name:identifier() _ {
-                let qn = QualifiedName {
-                    id: parser.fresh(),
-                    components: vec![Rc::new(name.to_string())],
-                };
-                (name, Pattern::VarOrName(qn))
-            }
-
-
-        rule pattern_literal() -> Pattern =
-            "true" { Pattern::Literal(PatternLiteral::BoolPattern(true)) } /
-            "false" { Pattern::Literal(PatternLiteral::BoolPattern(false)) } /
-            s:bare_string_literal() { Pattern::Literal(PatternLiteral::StringPattern(Rc::new(s))) } /
-            sign:("-"?)  num:(float_literal() / nat_literal()) {
-                let neg = sign.is_some();
-                Pattern::Literal(PatternLiteral::NumPattern { neg, num })
-            } /
-            "_" { Pattern::Ignored }
-
-
-        rule list_expr(parser: &mut Parser) -> ExpressionKind =
-            "[" exprs:(expression(parser) ** ",") "]" {
-                let mut exprs = exprs;
-                ExpressionKind::ListLiteral(exprs)
-            }
-
-        rule paren_expr(parser: &mut Parser) -> ExpressionKind =
-            "(" exprs:(expression(parser) ** ",") ")" {
-                let mut exprs = exprs;
-                match exprs.len() {
-                    1 => exprs.pop().unwrap().kind,
-                    _ => ExpressionKind::TupleLiteral(exprs),
-                }
-            }
-
-        rule string_literal() -> ExpressionKind =
-            prefix:identifier()? s:bare_string_literal(){ ExpressionKind::StringLiteral{ s: Rc::new(s),
-                prefix: prefix.map(rc_string)
-            } }
-
-        rule bare_string_literal() -> String =
-            "\"" chars:string_component()* "\"" { chars.into_iter().collect::<String>() }
-
-        rule string_component() -> char =
-            !(r#"""# / r#"\"#) ch:$([_]) { ch.chars().next().unwrap() } /
-            r#"\u{"# value:$(['0'..='9' | 'a'..='f' | 'A'..='F']+) "}" { char::from_u32(u32::from_str_radix(value, 16).unwrap()).unwrap() } /
-            r#"\n"# { '\n' } / r#"\t"# { '\t' } / r#"\""# { '"' } / r#"\\"# { '\\' } /
-      expected!("Valid escape sequence")
-
-        rule bool_literal() -> ExpressionKind =
-            "true" { ExpressionKind::BoolLiteral(true) } / "false" { ExpressionKind::BoolLiteral(false) }
-
-        rule nat_literal() -> ExpressionKind =
-            bin_literal() / hex_literal() / unmarked_literal()
-
-        rule unmarked_literal() -> ExpressionKind =
-            digits:digits() { let n = digits.chars().filter(|ch| *ch != '_').collect::<String>().parse().unwrap(); ExpressionKind::NatLiteral(n) }
-
-        rule bin_literal() -> ExpressionKind =
-            "0b" digits:bin_digits() {? parse_binary(digits).map(ExpressionKind::NatLiteral) }
-
-        rule hex_literal() -> ExpressionKind =
-            "0x" digits:hex_digits() {? parse_hex(digits).map(ExpressionKind::NatLiteral) }
-
-        rule float_literal() -> ExpressionKind =
-            ds:$( digits() "." digits()? / "." digits() ) { ExpressionKind::FloatLiteral(ds.parse().unwrap()) }
-
-        rule digits() -> &'input str = $((digit_group() "_"*)+)
-        rule bin_digits() -> &'input str = $((bin_digit_group() "_"*)+)
-        rule hex_digits() -> &'input str = $((hex_digit_group() "_"*)+)
-
-        rule digit_group() -> &'input str = $(['0'..='9']+)
-        rule bin_digit_group() -> &'input str = $(['0' | '1']+)
-        rule hex_digit_group() -> &'input str = $(['0'..='9' | 'a'..='f' | 'A'..='F']+)
-
-    }
-}
-
-fn parse_binary(digits: &str) -> Result<u64, &'static str> {
-    let mut result: u64 = 0;
-    let mut multiplier = 1;
-    for d in digits.chars().rev() {
-        match d {
-            '1' => result += multiplier,
-            '0' => (),
-            '_' => continue,
-            _ => unreachable!(),
-        }
-        multiplier = match multiplier.checked_mul(2) {
-            Some(m) => m,
-            None => return Err("Binary expression will overflow"),
-        }
-    }
-    Ok(result)
-}
-
-fn parse_hex(digits: &str) -> Result<u64, &'static str> {
-    let mut result: u64 = 0;
-    let mut multiplier: u64 = 1;
-    for d in digits.chars().rev() {
-        if d == '_' {
-            continue;
-        }
-        match d.to_digit(16) {
-            Some(n) => result += n as u64 * multiplier,
-            None => return Err("Internal parser error: invalid hex digit"),
-        }
-        multiplier = match multiplier.checked_mul(16) {
-            Some(m) => m,
-            None => return Err("Hexadecimal expression will overflow"),
-        }
-    }
-    Ok(result)
-}
-
-#[derive(Debug)]
-struct BinopSequence {
-    first: ExpressionKind,
-    next: Vec<(BinOp, ExpressionKind)>,
-}
-
-impl BinopSequence {
-    fn do_precedence(self, parser: &mut Parser) -> ExpressionKind {
-        fn helper(
-            precedence: i32,
-            lhs: ExpressionKind,
-            rest: &mut Vec<(BinOp, ExpressionKind)>,
-            parser: &mut Parser,
-        ) -> Expression {
-            let mut lhs = Expression::new(parser.fresh(), lhs);
-            while let Some((next_op, next_rhs)) = rest.pop() {
-                let new_precedence = next_op.get_precedence();
-                if precedence >= new_precedence {
-                    rest.push((next_op, next_rhs));
-                    break;
-                }
-                let rhs = helper(new_precedence, next_rhs, rest, parser);
-                lhs = Expression::new(
-                    parser.fresh(),
-                    ExpressionKind::BinExp(next_op, Box::new(lhs), Box::new(rhs)),
-                );
-            }
-            lhs
-        }
-        let mut as_stack = self.next.into_iter().rev().collect();
-        helper(BinOp::min_precedence(), self.first, &mut as_stack, parser).kind
-    }
-}
--- a/schala-lang/src/parsing/test.rs
+++ b/schala-lang/src/parsing/test.rs
--- a/schala-lang/src/reduced_ir/mod.rs
+++ b/schala-lang/src/reduced_ir/mod.rs
@ -1,484 +0,0 @@
-use std::{collections::HashMap, rc::Rc, str::FromStr};
-
-use crate::{
-    ast,
-    builtin::Builtin,
-    symbol_table::{DefId, SymbolSpec, SymbolTable},
-    type_inference::{TypeContext, TypeId},
-};
-
-mod test;
-mod types;
-
-pub use types::*;
-
-pub fn reduce(ast: &ast::AST, symbol_table: &SymbolTable, type_context: &TypeContext) -> ReducedIR {
-    let reducer = Reducer::new(symbol_table, type_context);
-    reducer.reduce(ast)
-}
-
-struct Reducer<'a, 'b> {
-    symbol_table: &'a SymbolTable,
-    functions: HashMap<DefId, FunctionDefinition>,
-    type_context: &'b TypeContext,
-}
-
-impl<'a, 'b> Reducer<'a, 'b> {
-    fn new(symbol_table: &'a SymbolTable, type_context: &'b TypeContext) -> Self {
-        Self { symbol_table, functions: HashMap::new(), type_context }
-    }
-
-    fn reduce(mut self, ast: &ast::AST) -> ReducedIR {
-        // First reduce all functions
-        // TODO once this works, maybe rewrite it using the Visitor
-        for statement in ast.statements.statements.iter() {
-            self.top_level_definition(statement);
-        }
-
-        // Then compute the entrypoint statements (which may reference previously-computed
-        // functions by ID)
-        let mut entrypoint = vec![];
-        for statement in ast.statements.statements.iter() {
-            let ast::Statement { id: item_id, kind, .. } = statement;
-            match &kind {
-                ast::StatementKind::Expression(expr) => {
-                    entrypoint.push(Statement::Expression(self.expression(expr)));
-                }
-                ast::StatementKind::Declaration(ast::Declaration::Binding {
-                    name: _,
-                    constant,
-                    expr,
-                    ..
-                }) => {
-                    let symbol = self.symbol_table.lookup_symbol(item_id).unwrap();
-                    entrypoint.push(Statement::Binding {
-                        id: symbol.def_id(),
-                        constant: *constant,
-                        expr: self.expression(expr),
-                    });
-                }
-                _ => (),
-            }
-        }
-
-        ReducedIR { functions: self.functions, entrypoint }
-    }
-
-    fn top_level_definition(&mut self, statement: &ast::Statement<ast::StatementKind>) {
-        let ast::Statement { id: item_id, kind, .. } = statement;
-        match kind {
-            ast::StatementKind::Expression(_expr) => {
-                //TODO expressions can in principle contain definitions, but I won't worry
-                //about it now
-            }
-            ast::StatementKind::Declaration(decl) => match decl {
-                ast::Declaration::FuncDecl(_, statements) => {
-                    self.insert_function_definition(item_id, statements);
-                }
-                ast::Declaration::Impl { type_name: _, interface_name: _, block } =>
-                    for item in block {
-                        if let ast::Statement {
-                            id: item_id,
-                            kind: ast::Declaration::FuncDecl(_, statements),
-                            ..
-                        } = item
-                        {
-                            self.insert_function_definition(item_id, statements);
-                        }
-                    },
-                _ => (),
-            },
-            // Imports should have already been processed by the symbol table and are irrelevant
-            // for this representation.
-            ast::StatementKind::Import(..) => (),
-            ast::StatementKind::Flow(..) => {
-                //TODO this should be an error
-            }
-        }
-    }
-
-    fn function_internal_statement(
-        &mut self,
-        statement: &ast::Statement<ast::StatementKind>,
-    ) -> Option<Statement> {
-        let ast::Statement { id: item_id, kind, .. } = statement;
-        match kind {
-            ast::StatementKind::Expression(expr) => Some(Statement::Expression(self.expression(expr))),
-            ast::StatementKind::Declaration(decl) => match decl {
-                ast::Declaration::FuncDecl(_, statements) => {
-                    self.insert_function_definition(item_id, statements);
-                    None
-                }
-                ast::Declaration::Binding { constant, expr, .. } => {
-                    let symbol = self.symbol_table.lookup_symbol(item_id).unwrap();
-                    Some(Statement::Binding {
-                        id: symbol.def_id(),
-                        constant: *constant,
-                        expr: self.expression(expr),
-                    })
-                }
-                _ => None,
-            },
-            ast::StatementKind::Import(_) => None,
-            ast::StatementKind::Flow(ast::FlowControl::Return(expr)) =>
-                if let Some(expr) = expr {
-                    Some(Statement::Return(self.expression(expr)))
-                } else {
-                    Some(Statement::Return(Expression::unit()))
-                },
-            ast::StatementKind::Flow(ast::FlowControl::Break) => Some(Statement::Break),
-            ast::StatementKind::Flow(ast::FlowControl::Continue) => Some(Statement::Continue),
-        }
-    }
-
-    fn insert_function_definition(&mut self, item_id: &ast::ItemId, statements: &ast::Block) {
-        let symbol = self.symbol_table.lookup_symbol(item_id).unwrap();
-        let function_def = FunctionDefinition { body: self.function_internal_block(statements) };
-        self.functions.insert(symbol.def_id(), function_def);
-    }
-
-    //TODO this needs to be type-aware to work correctly
-    fn lookup_method(&mut self, name: &str) -> Option<DefId> {
-        for (def_id, function) in self.functions.iter() {
-            let symbol = self.symbol_table.lookup_symbol_by_def(def_id)?;
-            println!("Def Id: {} symbol: {:?}", def_id, symbol);
-            if symbol.local_name() == name {
-                return Some(*def_id);
-            }
-        }
-        None
-    }
-
-    fn expression(&mut self, expr: &ast::Expression) -> Expression {
-        use crate::ast::ExpressionKind::*;
-
-        match &expr.kind {
-            SelfValue => Expression::Lookup(Lookup::SelfParam),
-            NatLiteral(n) => Expression::Literal(Literal::Nat(*n)),
-            FloatLiteral(f) => Expression::Literal(Literal::Float(*f)),
-            //TODO implement handling string literal prefixes
-            StringLiteral { s, prefix: _ } => Expression::Literal(Literal::StringLit(s.clone())),
-            BoolLiteral(b) => Expression::Literal(Literal::Bool(*b)),
-            BinExp(binop, lhs, rhs) => self.binop(binop, lhs, rhs),
-            PrefixExp(op, arg) => self.prefix(op, arg),
-            Value(qualified_name) => self.value(qualified_name),
-            Call { f, arguments } => {
-                let f = self.expression(f);
-                let args = arguments.iter().map(|arg| self.invocation_argument(arg)).collect();
-                //TODO need to have full type availability at this point to do this method lookup
-                //correctly
-                if let Expression::Access { name, expr } = f {
-                    let def_id = self.lookup_method(&name).unwrap();
-                    let method = Expression::Lookup(Lookup::Function(def_id));
-                    Expression::CallMethod { f: Box::new(method), args, self_expr: expr }
-                } else {
-                    Expression::Call { f: Box::new(f), args }
-                }
-            }
-            TupleLiteral(exprs) => Expression::Tuple(exprs.iter().map(|e| self.expression(e)).collect()),
-            IfExpression { discriminator, body } =>
-                self.reduce_if_expression(discriminator.as_ref().map(|x| x.as_ref()), body),
-            Lambda { params, body, .. } => Expression::Callable(Callable::Lambda {
-                arity: params.len() as u8,
-                body: self.function_internal_block(body),
-            }),
-            NamedStruct { name, fields } => {
-                let symbol = match self.symbol_table.lookup_symbol(&name.id) {
-                    Some(symbol) => symbol,
-                    None => return Expression::ReductionError(format!("No symbol found for {}", name)),
-                };
-                let (tag, type_id) = match symbol.spec() {
-                    SymbolSpec::RecordConstructor { tag, type_id } => (tag, type_id),
-                    e => return Expression::ReductionError(format!("Bad symbol for NamedStruct: {:?}", e)),
-                };
-
-                let field_order = compute_field_orderings(self.type_context, &type_id, tag).unwrap();
-
-                let mut field_map = HashMap::new();
-                for (name, expr) in fields.iter() {
-                    field_map.insert(name.as_ref(), expr);
-                }
-
-                let mut ordered_args = vec![];
-                for field in field_order.iter() {
-                    let expr = match field_map.get(&field) {
-                        Some(expr) => expr,
-                        None =>
-                            return Expression::ReductionError(format!(
-                                "Field {} not specified for record {}",
-                                field, name
-                            )),
-                    };
-                    ordered_args.push(self.expression(expr));
-                }
-
-                let constructor =
-                    Expression::Callable(Callable::RecordConstructor { type_id, tag, field_order });
-                Expression::Call { f: Box::new(constructor), args: ordered_args }
-            }
-            Index { indexee, indexers } => self.reduce_index(indexee.as_ref(), indexers.as_slice()),
-            WhileExpression { condition, body } => {
-                let cond = Box::new(if let Some(condition) = condition {
-                    self.expression(condition)
-                } else {
-                    Expression::Literal(Literal::Bool(true))
-                });
-                let statements = self.function_internal_block(body);
-                Expression::Loop { cond, statements }
-            }
-            ForExpression { .. } => Expression::ReductionError("For expr not implemented".to_string()),
-            ListLiteral(items) => Expression::List(items.iter().map(|item| self.expression(item)).collect()),
-            Access { name, expr } =>
-                Expression::Access { name: name.as_ref().to_string(), expr: Box::new(self.expression(expr)) },
-        }
-    }
-
-    //TODO figure out the semantics of multiple indexers - for now, just ignore them
-    fn reduce_index(&mut self, indexee: &ast::Expression, indexers: &[ast::Expression]) -> Expression {
-        if indexers.len() != 1 {
-            return Expression::ReductionError("Invalid index expression".to_string());
-        }
-        let indexee = self.expression(indexee);
-        let indexer = self.expression(&indexers[0]);
-        Expression::Index { indexee: Box::new(indexee), indexer: Box::new(indexer) }
-    }
-
-    fn reduce_if_expression(
-        &mut self,
-        discriminator: Option<&ast::Expression>,
-        body: &ast::IfExpressionBody,
-    ) -> Expression {
-        use ast::IfExpressionBody::*;
-
-        let cond = Box::new(match discriminator {
-            Some(expr) => self.expression(expr),
-            None => return Expression::ReductionError("blank cond if-expr not supported".to_string()),
-        });
-        match body {
-            SimpleConditional { then_case, else_case } => {
-                let then_clause = self.function_internal_block(then_case);
-                let else_clause = match else_case.as_ref() {
-                    None => vec![],
-                    Some(stmts) => self.function_internal_block(stmts),
-                };
-                Expression::Conditional { cond, then_clause, else_clause }
-            }
-            SimplePatternMatch { pattern, then_case, else_case } => {
-                let alternatives = vec![
-                    Alternative {
-                        pattern: match pattern.reduce(self.symbol_table) {
-                            Ok(p) => p,
-                            Err(e) => return Expression::ReductionError(format!("Bad pattern: {:?}", e)),
-                        },
-                        item: self.function_internal_block(then_case),
-                    },
-                    Alternative {
-                        pattern: Pattern::Ignored,
-                        item: match else_case.as_ref() {
-                            Some(else_case) => self.function_internal_block(else_case),
-                            None => vec![],
-                        },
-                    },
-                ];
-
-                Expression::CaseMatch { cond, alternatives }
-            }
-            CondList(ref condition_arms) => {
-                let mut alternatives = vec![];
-                for arm in condition_arms {
-                    match arm.condition {
-                        ast::Condition::Pattern(ref pat) => {
-                            let alt = Alternative {
-                                pattern: match pat.reduce(self.symbol_table) {
-                                    Ok(p) => p,
-                                    Err(e) =>
-                                        return Expression::ReductionError(format!("Bad pattern: {:?}", e)),
-                                },
-                                item: self.function_internal_block(&arm.body),
-                            };
-                            alternatives.push(alt);
-                        }
-                        ast::Condition::TruncatedOp(_, _) =>
-                            return Expression::ReductionError("case-expression-trunc-op".to_string()),
-                        ast::Condition::Else =>
-                            return Expression::ReductionError("case-expression-else".to_string()),
-                    }
-                }
-                Expression::CaseMatch { cond, alternatives }
-            }
-        }
-    }
-
-    fn invocation_argument(&mut self, invoc: &ast::InvocationArgument) -> Expression {
-        use crate::ast::InvocationArgument::*;
-        match invoc {
-            Positional(ex) => self.expression(ex),
-            Keyword { .. } => Expression::ReductionError("Keyword arguments not supported".to_string()),
-            Ignored => Expression::ReductionError("Ignored arguments not supported".to_string()),
-        }
-    }
-
-    fn function_internal_block(&mut self, block: &ast::Block) -> Vec<Statement> {
-        block.statements.iter().filter_map(|stmt| self.function_internal_statement(stmt)).collect()
-    }
-
-    fn prefix(&mut self, prefix: &ast::PrefixOp, arg: &ast::Expression) -> Expression {
-        let builtin: Option<Builtin> = TryFrom::try_from(prefix).ok();
-        match builtin {
-            Some(op) => Expression::Call {
-                f: Box::new(Expression::Callable(Callable::Builtin(op))),
-                args: vec![self.expression(arg)],
-            },
-            None => {
-                //TODO need this for custom prefix ops
-                Expression::ReductionError("User-defined prefix ops not supported".to_string())
-            }
-        }
-    }
-
-    fn binop(&mut self, binop: &ast::BinOp, lhs: &ast::Expression, rhs: &ast::Expression) -> Expression {
-        use Expression::ReductionError;
-
-        let operation = Builtin::from_str(binop.sigil()).ok();
-        match operation {
-            Some(Builtin::Assignment) => {
-                let lval = match &lhs.kind {
-                    ast::ExpressionKind::Value(qualified_name) => {
-                        if let Some(symbol) = self.symbol_table.lookup_symbol(&qualified_name.id) {
-                            symbol.def_id()
-                        } else {
-                            return ReductionError(format!("Couldn't look up name: {:?}", qualified_name));
-                        }
-                    }
-                    _ => return ReductionError("Trying to assign to a non-name".to_string()),
-                };
-
-                Expression::Assign { lval, rval: Box::new(self.expression(rhs)) }
-            }
-            Some(op) => Expression::Call {
-                f: Box::new(Expression::Callable(Callable::Builtin(op))),
-                args: vec![self.expression(lhs), self.expression(rhs)],
-            },
-            //TODO handle a user-defined operation
-            None => ReductionError("User-defined operations not supported".to_string()),
-        }
-    }
-
-    fn value(&mut self, qualified_name: &ast::QualifiedName) -> Expression {
-        use SymbolSpec::*;
-
-        let symbol = match self.symbol_table.lookup_symbol(&qualified_name.id) {
-            Some(s) => s,
-            None =>
-                return Expression::ReductionError(format!("No symbol found for name: `{}`", qualified_name)),
-        };
-
-        let def_id = symbol.def_id();
-
-        match symbol.spec() {
-            Builtin(b) => Expression::Callable(Callable::Builtin(b)),
-            Func { .. } => Expression::Lookup(Lookup::Function(def_id)),
-            GlobalBinding => Expression::Lookup(Lookup::GlobalVar(def_id)),
-            LocalVariable => Expression::Lookup(Lookup::LocalVar(def_id)),
-            FunctionParam(n) => Expression::Lookup(Lookup::Param(n)),
-            DataConstructor { tag, type_id } =>
-                Expression::Callable(Callable::DataConstructor { type_id, tag }),
-            RecordConstructor { .. } => Expression::ReductionError(format!(
-                "The symbol for value {:?} is unexpectdly a RecordConstructor",
-                qualified_name
-            )),
-        }
-    }
-}
-
-impl ast::Pattern {
-    fn reduce(&self, symbol_table: &SymbolTable) -> Result<Pattern, PatternError> {
-        Ok(match self {
-            ast::Pattern::Ignored => Pattern::Ignored,
-            ast::Pattern::TuplePattern(subpatterns) => {
-                let items: Result<Vec<Pattern>, PatternError> =
-                    subpatterns.iter().map(|pat| pat.reduce(symbol_table)).into_iter().collect();
-                let items = items?;
-                Pattern::Tuple { tag: None, subpatterns: items }
-            }
-            ast::Pattern::Literal(lit) => Pattern::Literal(match lit {
-                ast::PatternLiteral::NumPattern { neg, num } => match (neg, num) {
-                    (false, ast::ExpressionKind::NatLiteral(n)) => Literal::Nat(*n),
-                    (false, ast::ExpressionKind::FloatLiteral(f)) => Literal::Float(*f),
-                    (true, ast::ExpressionKind::NatLiteral(n)) => Literal::Int(-(*n as i64)),
-                    (true, ast::ExpressionKind::FloatLiteral(f)) => Literal::Float(-f),
-                    (_, e) =>
-                        return Err(format!("Internal error, unexpected pattern literal: {:?}", e).into()),
-                },
-                ast::PatternLiteral::StringPattern(s) => Literal::StringLit(s.clone()),
-                ast::PatternLiteral::BoolPattern(b) => Literal::Bool(*b),
-            }),
-            ast::Pattern::TupleStruct(name, subpatterns) => {
-                let symbol = symbol_table.lookup_symbol(&name.id).unwrap();
-                if let SymbolSpec::DataConstructor { tag, type_id: _ } = symbol.spec() {
-                    let items: Result<Vec<Pattern>, PatternError> =
-                        subpatterns.iter().map(|pat| pat.reduce(symbol_table)).into_iter().collect();
-                    let items = items?;
-                    Pattern::Tuple { tag: Some(tag), subpatterns: items }
-                } else {
-                    return Err(
-                        "Internal error, trying to match something that's not a DataConstructor".into()
-                    );
-                }
-            }
-            ast::Pattern::VarOrName(name) => {
-                let symbol = symbol_table.lookup_symbol(&name.id).unwrap();
-                match symbol.spec() {
-                    SymbolSpec::DataConstructor { tag, type_id: _ } =>
-                        Pattern::Tuple { tag: Some(tag), subpatterns: vec![] },
-                    SymbolSpec::LocalVariable => {
-                        let def_id = symbol.def_id();
-                        Pattern::Binding(def_id)
-                    }
-                    spec => return Err(format!("Unexpected VarOrName symbol: {:?}", spec).into()),
-                }
-            }
-            ast::Pattern::Record(name, specified_members) => {
-                let symbol = symbol_table.lookup_symbol(&name.id).unwrap();
-                if let SymbolSpec::RecordConstructor { tag, type_id: _ } = symbol.spec() {
-                    //TODO do this computation from the type_id
-                    /*
-                    if specified_members.iter().any(|(member, _)| !members.contains_key(member)) {
-                        return Err(format!("Unknown key in record pattern").into());
-                    }
-                    */
-
-                    let subpatterns: Result<Vec<(Rc<String>, Pattern)>, PatternError> = specified_members
-                        .iter()
-                        .map(|(name, pat)| {
-                            pat.reduce(symbol_table).map(|reduced_pat| (name.clone(), reduced_pat))
-                        })
-                        .into_iter()
-                        .collect();
-                    let subpatterns = subpatterns?;
-                    Pattern::Record { tag, subpatterns }
-                } else {
-                    return Err(format!("Unexpected Record pattern symbol: {:?}", symbol.spec()).into());
-                }
-            }
-        })
-    }
-}
-
-/// Given the type context and a variant, compute what order the fields on it were stored.
-/// This needs to be public until type-checking is fully implemented because the type information
-/// is only available at runtime.
-pub fn compute_field_orderings(
-    type_context: &TypeContext,
-    type_id: &TypeId,
-    tag: u32,
-) -> Option<Vec<String>> {
-    // Eventually, the ReducedIR should decide what field ordering is optimal.
-    // For now, just do it alphabetically.
-
-    let record_members = type_context.lookup_record_members(type_id, tag)?;
-    let mut field_order: Vec<String> =
-        record_members.iter().map(|(field, _type_id)| field).cloned().collect();
-    field_order.sort_unstable();
-    Some(field_order)
-}
--- a/schala-lang/src/reduced_ir/test.rs
+++ b/schala-lang/src/reduced_ir/test.rs
@ -1,61 +0,0 @@
-#![cfg(test)]
-
-use super::*;
-use crate::{symbol_table::SymbolTable, type_inference::TypeContext};
-
-fn build_ir(input: &str) -> ReducedIR {
-    let ast = crate::util::quick_ast(input);
-
-    let mut symbol_table = SymbolTable::new();
-    let mut type_context = TypeContext::new();
-
-    symbol_table.process_ast(&ast, &mut type_context).unwrap();
-
-    let reduced = reduce(&ast, &symbol_table, &type_context);
-    reduced.debug(&symbol_table);
-    reduced
-}
-
-#[test]
-fn test_ir() {
-    let src = r#"
-
-    let global_one = 10 + 20
-    let global_two = "the string hello"
-
-    fn a_function(i, j, k) {
-        fn nested(x) {
-            x + 10
-        }
-        i + j * nested(k)
-    }
-
-    fn another_function(e) {
-        let local_var = 420
-        e * local_var
-    }
-
-    another_function()
-    "#;
-
-    let reduced = build_ir(src);
-    assert_eq!(reduced.functions.len(), 3);
-}
-
-#[test]
-fn test_methods() {
-    let src = r#"
-type Thing = Thing
-impl Thing {
-    fn a_method() {
-        20
-    }
-
-}
-
-let a = Thing
-4 + a.a_method()
-    "#;
-    let reduced = build_ir(src);
-    assert_eq!(reduced.functions.len(), 1);
-}
--- a/schala-lang/src/reduced_ir/types.rs
+++ b/schala-lang/src/reduced_ir/types.rs
@ -1,137 +0,0 @@
-use std::{collections::HashMap, convert::From, rc::Rc};
-
-use crate::{
-    builtin::Builtin,
-    symbol_table::{DefId, SymbolTable},
-    type_inference::TypeId,
-};
-
-//TODO most of these Clone impls only exist to support function application, because the
-//tree-walking evaluator moves the reduced IR members.
-
-/// The reduced intermediate representation consists of a list of function definitions, and a block
-/// of entrypoint statements.  In a repl or script context this can be an arbitrary list of
-/// statements, in an executable context will likely just be a pointer to the main() function.
-#[derive(Debug)]
-pub struct ReducedIR {
-    pub functions: HashMap<DefId, FunctionDefinition>,
-    pub entrypoint: Vec<Statement>,
-}
-
-impl ReducedIR {
-    #[allow(dead_code)]
-    pub fn debug(&self, symbol_table: &SymbolTable) {
-        println!("Reduced IR:");
-        println!("Functions:");
-        println!("-----------");
-        for (id, callable) in self.functions.iter() {
-            let name = &symbol_table.lookup_symbol_by_def(id).unwrap().local_name();
-            println!("{}({}) -> {:?}", id, name, callable);
-        }
-        println!();
-        println!("Entrypoint:");
-        println!("-----------");
-        for stmt in self.entrypoint.iter() {
-            println!("{:?}", stmt);
-        }
-        println!("-----------");
-    }
-}
-
-#[derive(Debug, Clone)]
-pub enum Statement {
-    Expression(Expression),
-    Binding { id: DefId, constant: bool, expr: Expression },
-    Return(Expression),
-    Continue,
-    Break,
-}
-
-#[derive(Debug, Clone)]
-pub enum Expression {
-    Literal(Literal),
-    Tuple(Vec<Expression>),
-    List(Vec<Expression>),
-    Lookup(Lookup),
-    Assign { lval: DefId, rval: Box<Expression> },
-    Access { name: String, expr: Box<Expression> },
-    Callable(Callable),
-    Call { f: Box<Expression>, args: Vec<Expression> },
-    CallMethod { f: Box<Expression>, args: Vec<Expression>, self_expr: Box<Expression> },
-    Conditional { cond: Box<Expression>, then_clause: Vec<Statement>, else_clause: Vec<Statement> },
-    CaseMatch { cond: Box<Expression>, alternatives: Vec<Alternative> },
-    Loop { cond: Box<Expression>, statements: Vec<Statement> },
-    Index { indexee: Box<Expression>, indexer: Box<Expression> },
-    ReductionError(String),
-}
-
-impl Expression {
-    pub fn unit() -> Self {
-        Expression::Tuple(vec![])
-    }
-}
-
-#[derive(Debug)]
-pub struct FunctionDefinition {
-    pub body: Vec<Statement>,
-}
-
-#[derive(Debug, Clone)]
-pub enum Callable {
-    Builtin(Builtin),
-    UserDefined(DefId),
-    Lambda { arity: u8, body: Vec<Statement> },
-    DataConstructor { type_id: TypeId, tag: u32 },
-    RecordConstructor { type_id: TypeId, tag: u32, field_order: Vec<String> },
-}
-
-#[derive(Debug, Clone)]
-pub enum Lookup {
-    LocalVar(DefId),
-    GlobalVar(DefId),
-    Function(DefId),
-    Param(u8),
-    SelfParam,
-}
-
-#[derive(Debug, Clone, PartialEq)]
-pub enum Literal {
-    Nat(u64),
-    Int(i64),
-    Float(f64),
-    Bool(bool),
-    StringLit(Rc<String>),
-}
-
-#[derive(Debug, Clone)]
-pub struct Alternative {
-    pub pattern: Pattern,
-    pub item: Vec<Statement>,
-}
-
-#[derive(Debug, Clone)]
-pub enum Pattern {
-    Tuple { subpatterns: Vec<Pattern>, tag: Option<u32> },
-    Record { tag: u32, subpatterns: Vec<(Rc<String>, Pattern)> },
-    Literal(Literal),
-    Ignored,
-    Binding(DefId),
-}
-
-#[allow(dead_code)]
-#[derive(Debug)]
-pub struct PatternError {
-    msg: String,
-}
-
-impl From<&str> for PatternError {
-    fn from(s: &str) -> Self {
-        Self { msg: s.to_string() }
-    }
-}
-
-impl From<String> for PatternError {
-    fn from(msg: String) -> Self {
-        Self { msg }
-    }
-}
--- a/schala-lang/src/schala.rs
+++ b/schala-lang/src/schala.rs
@ -1,210 +0,0 @@
-use schala_repl::{
-    ComputationRequest, ComputationResponse, GlobalOutputStats, LangMetaRequest, LangMetaResponse,
-    ProgrammingLanguageInterface,
-};
-use stopwatch::Stopwatch;
-
-use crate::{error::SchalaError, parsing, reduced_ir, symbol_table, tree_walk_eval, type_inference};
-
-/// All the state necessary to parse and execute a Schala program are stored in this struct.
-pub struct Schala<'a> {
-    /// Holds a reference to the original source code, parsed into line and character
-    source_reference: SourceReference,
-
-    //state: eval::State<'static>,
-    /// Keeps track of symbols and scopes
-    symbol_table: symbol_table::SymbolTable,
-    /// Contains information for type-checking
-    type_context: type_inference::TypeContext,
-    /// Schala Parser
-    active_parser: parsing::Parser,
-
-    /// Execution state for AST-walking interpreter
-    eval_state: tree_walk_eval::State<'a>,
-
-    timings: Vec<(&'static str, std::time::Duration)>,
-}
-
-/*
-impl Schala {
-    //TODO implement documentation for language items
-    /*
-    fn handle_docs(&self, source: String) -> LangMetaResponse {
-      LangMetaResponse::Docs {
-        doc_string: format!("Schala item `{}` : <<Schala-lang documentation not yet implemented>>", source)
-      }
-    }
-    */
-}
-*/
-
-impl<'a> Schala<'a> {
-    /// Creates a new Schala environment *without* any prelude.
-    fn new_blank_env() -> Schala<'a> {
-        Schala {
-            source_reference: SourceReference::new(),
-            symbol_table: symbol_table::SymbolTable::new(),
-            type_context: type_inference::TypeContext::new(),
-            active_parser: parsing::Parser::new(),
-            eval_state: tree_walk_eval::State::new(),
-            timings: Vec::new(),
-        }
-    }
-
-    /// Creates a new Schala environment with the standard prelude, which is defined as ordinary
-    /// Schala code in the file `prelude.schala`
-    #[allow(clippy::new_without_default)]
-    pub fn new() -> Schala<'a> {
-        let prelude = include_str!("../source-files/prelude.schala");
-        let mut env = Schala::new_blank_env();
-
-        let response = env.run_pipeline(prelude, SchalaConfig::default());
-        if let Err(err) = response {
-            panic!("Error in prelude, panicking: {}", err.display());
-        }
-        env
-    }
-
-    /// This is where the actual action of interpreting/compilation happens.
-    /// Note: this should eventually use a query-based system for parallelization, cf.
-    /// https://rustc-dev-guide.rust-lang.org/overview.html
-    fn run_pipeline(&mut self, source: &str, config: SchalaConfig) -> Result<String, SchalaError> {
-        self.timings = vec![];
-        let sw = Stopwatch::start_new();
-
-        self.source_reference.load_new_source(source);
-        let ast = self
-            .active_parser
-            .parse(source)
-            .map_err(|err| SchalaError::from_parse_error(err, &self.source_reference))?;
-        self.timings.push(("parsing", sw.elapsed()));
-
-        let sw = Stopwatch::start_new();
-        //Perform all symbol table work
-        self.symbol_table
-            .process_ast(&ast, &mut self.type_context)
-            .map_err(SchalaError::from_symbol_table)?;
-
-        self.timings.push(("symbol_table", sw.elapsed()));
-
-        // Typechecking
-        let _overall_type = self.type_context.typecheck(&ast).map_err(SchalaError::from_type_error);
-
-        let sw = Stopwatch::start_new();
-        let reduced_ir = reduced_ir::reduce(&ast, &self.symbol_table, &self.type_context);
-        self.timings.push(("reduced_ir", sw.elapsed()));
-
-        let sw = Stopwatch::start_new();
-        let evaluation_outputs = self.eval_state.evaluate(reduced_ir, &self.type_context, config.repl);
-        self.timings.push(("tree-walking-evaluation", sw.elapsed()));
-        let text_output: Result<Vec<String>, String> = evaluation_outputs.into_iter().collect();
-
-        let text_output: Result<Vec<String>, SchalaError> =
-            text_output.map_err(|err| SchalaError::from_string(err, Stage::Evaluation));
-
-        let eval_output: String =
-            text_output.map(|v| Iterator::intersperse(v.into_iter(), "\n".to_owned()).collect())?;
-
-        Ok(eval_output)
-    }
-}
-
-/// Represents lines of source code
-pub(crate) struct SourceReference {
-    last_source: Option<String>,
-    /// Offsets in *bytes* (not chars) representing a newline character
-    newline_offsets: Vec<usize>,
-}
-
-impl SourceReference {
-    pub(crate) fn new() -> SourceReference {
-        SourceReference { last_source: None, newline_offsets: vec![] }
-    }
-
-    pub(crate) fn load_new_source(&mut self, source: &str) {
-        self.newline_offsets = vec![];
-        for (offset, ch) in source.as_bytes().iter().enumerate() {
-            if *ch == b'\n' {
-                self.newline_offsets.push(offset);
-            }
-        }
-        self.last_source = Some(source.to_string());
-    }
-
-    // (line_start, line_num, the string itself)
-    pub fn get_line(&self, line: usize) -> (usize, usize, String) {
-        if self.newline_offsets.is_empty() {
-            return (0, 0, self.last_source.as_ref().cloned().unwrap());
-        }
-
-        //TODO make sure this is utf8-safe
-        let start_idx = match self.newline_offsets.binary_search(&line) {
-            Ok(index) | Err(index) => index,
-        };
-
-        let last_source = self.last_source.as_ref().unwrap();
-
-        let start = self.newline_offsets[start_idx];
-        let end = self.newline_offsets.get(start_idx + 1).cloned().unwrap_or_else(|| last_source.len());
-
-        let slice = &last_source.as_bytes()[start..end];
-        (start, start_idx, std::str::from_utf8(slice).unwrap().to_string())
-    }
-}
-
-#[allow(dead_code)]
-#[derive(Clone, Copy, Debug)]
-pub(crate) enum Stage {
-    Parsing,
-    Symbols,
-    ScopeResolution,
-    Typechecking,
-    AstReduction,
-    Evaluation,
-}
-
-fn stage_names() -> Vec<&'static str> {
-    vec!["parsing", "symbol-table", "typechecking", "ast-reduction", "ast-walking-evaluation"]
-}
-
-#[derive(Default, Clone)]
-pub struct SchalaConfig {
-    pub repl: bool,
-}
-
-impl<'a> ProgrammingLanguageInterface for Schala<'a> {
-    //TODO flesh out Config
-    type Config = SchalaConfig;
-    fn language_name() -> String {
-        "Schala".to_owned()
-    }
-
-    fn source_file_suffix() -> String {
-        "schala".to_owned()
-    }
-
-    fn run_computation(&mut self, request: ComputationRequest<Self::Config>) -> ComputationResponse {
-        let ComputationRequest { source, debug_requests: _, config: _ } = request;
-        let sw = Stopwatch::start_new();
-
-        let main_output =
-            self.run_pipeline(source, request.config).map_err(|schala_err| schala_err.display());
-        let total_duration = sw.elapsed();
-
-        let stage_durations: Vec<_> = std::mem::take(&mut self.timings)
-            .into_iter()
-            .map(|(label, duration)| (label.to_string(), duration))
-            .collect();
-        let global_output_stats = GlobalOutputStats { total_duration, stage_durations };
-
-        ComputationResponse { main_output, global_output_stats, debug_responses: vec![] }
-    }
-
-    fn request_meta(&mut self, request: LangMetaRequest) -> LangMetaResponse {
-        match request {
-            LangMetaRequest::StageNames =>
-                LangMetaResponse::StageNames(stage_names().iter().map(|s| s.to_string()).collect()),
-            _ => LangMetaResponse::Custom { kind: "not-implemented".to_string(), value: "".to_string() },
-        }
-    }
-}
--- a/schala-lang/src/symbol_table/fqsn.rs
+++ b/schala-lang/src/symbol_table/fqsn.rs
@ -1,65 +0,0 @@
-use std::{fmt, rc::Rc};
-
-/// Fully-qualified symbol name
-#[derive(Debug, Clone, Eq, PartialEq, Hash, PartialOrd, Ord)]
-pub struct Fqsn {
-    //TODO Fqsn's need to be cheaply cloneable
-    pub scopes: Vec<ScopeSegment>,
-}
-
-impl Fqsn {
-    pub fn from_scope_stack(scopes: &[ScopeSegment], new_name: Rc<String>) -> Self {
-        let mut v = Vec::new();
-        for s in scopes {
-            v.push(s.clone());
-        }
-        v.push(ScopeSegment::Name(new_name));
-        Fqsn { scopes: v }
-    }
-
-    pub fn extend(&self, new_item: &str) -> Self {
-        let mut new = self.clone();
-        new.scopes.push(ScopeSegment::Name(Rc::new(new_item.to_string())));
-        new
-    }
-
-    #[allow(dead_code)]
-    pub fn from_strs(strs: &[&str]) -> Fqsn {
-        let mut scopes = vec![];
-        for s in strs {
-            scopes.push(ScopeSegment::Name(Rc::new(s.to_string())));
-        }
-        Fqsn { scopes }
-    }
-
-    pub fn last_elem(&self) -> Rc<String> {
-        let ScopeSegment::Name(name) = self.scopes.last().unwrap();
-        name.clone()
-    }
-}
-
-impl fmt::Display for Fqsn {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let delim = "::";
-        let Fqsn { scopes } = self;
-        write!(f, "FQSN<{}", scopes[0])?;
-        for item in scopes[1..].iter() {
-            write!(f, "{}{}", delim, item)?;
-        }
-        write!(f, ">")
-    }
-}
-
-//TODO eventually this should use ItemId's to avoid String-cloning
-/// One segment within a scope.
-#[derive(Debug, Clone, Eq, PartialEq, Hash, PartialOrd, Ord)]
-pub enum ScopeSegment {
-    Name(Rc<String>),
-}
-
-impl fmt::Display for ScopeSegment {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let ScopeSegment::Name(name) = self;
-        write!(f, "{}", name)
-    }
-}
--- a/schala-lang/src/symbol_table/mod.rs
+++ b/schala-lang/src/symbol_table/mod.rs
@ -1,244 +0,0 @@
-#![allow(clippy::enum_variant_names)]
-
-use std::{
-    collections::{hash_map::Entry, HashMap},
-    fmt,
-    rc::Rc,
-};
-
-use crate::{
-    ast,
-    ast::ItemId,
-    builtin::Builtin,
-    parsing::Location,
-    type_inference::{TypeContext, TypeId},
-};
-
-mod populator;
-use populator::SymbolTablePopulator;
-mod fqsn;
-pub use fqsn::{Fqsn, ScopeSegment};
-mod resolver;
-mod symbol_trie;
-use symbol_trie::SymbolTrie;
-mod test;
-use crate::identifier::{define_id_kind, Id, IdStore};
-
-define_id_kind!(DefItem);
-pub type DefId = Id<DefItem>;
-
-#[allow(dead_code)]
-#[derive(Debug, Clone)]
-pub enum SymbolError {
-    DuplicateName { prev_name: Fqsn, location: Location },
-    DuplicateVariant { type_fqsn: Fqsn, name: String },
-    DuplicateRecord { type_fqsn: Fqsn, location: Location, record: String, member: String },
-    UnknownAnnotation { name: String },
-    BadAnnotation { name: String, msg: String },
-    BadImplBlockEntry,
-}
-
-#[allow(dead_code)]
-#[derive(Debug)]
-struct NameSpec<K> {
-    location: Location,
-    kind: K,
-}
-
-#[derive(Debug)]
-enum NameKind {
-    Module,
-    Function,
-    Binding,
-}
-
-#[derive(Debug)]
-enum TypeKind {
-    Function,
-    Constructor,
-}
-
-/// Keeps track of what names were used in a given namespace.
-struct NameTable<K> {
-    table: HashMap<Fqsn, NameSpec<K>>,
-}
-
-impl<K> NameTable<K> {
-    fn new() -> Self {
-        Self { table: HashMap::new() }
-    }
-
-    fn register(&mut self, name: Fqsn, spec: NameSpec<K>) -> Result<(), SymbolError> {
-        match self.table.entry(name.clone()) {
-            Entry::Occupied(o) =>
-                Err(SymbolError::DuplicateName { prev_name: name, location: o.get().location }),
-            Entry::Vacant(v) => {
-                v.insert(spec);
-                Ok(())
-            }
-        }
-    }
-}
-
-//cf. p. 150 or so of Language Implementation Patterns
-pub struct SymbolTable {
-    def_id_store: IdStore<DefItem>,
-
-    /// Used for import resolution.
-    symbol_trie: SymbolTrie,
-
-    /// These tables are responsible for preventing duplicate names.
-    fq_names: NameTable<NameKind>, //Note that presence of two tables implies that a type and other binding with the same name can co-exist
-    types: NameTable<TypeKind>,
-
-    id_to_def: HashMap<ItemId, DefId>,
-    def_to_symbol: HashMap<DefId, Rc<Symbol>>,
-}
-
-impl SymbolTable {
-    /// Create a new, empty SymbolTable
-    pub fn new() -> Self {
-        Self {
-            def_id_store: IdStore::new(),
-            symbol_trie: SymbolTrie::new(),
-            fq_names: NameTable::new(),
-            types: NameTable::new(),
-            id_to_def: HashMap::new(),
-            def_to_symbol: HashMap::new(),
-        }
-    }
-
-    /// The main entry point into the symbol table. This will traverse the AST in several
-    /// different ways and populate subtables with information that will be used further in the
-    /// compilation process.
-    pub fn process_ast(
-        &mut self,
-        ast: &ast::AST,
-        type_context: &mut TypeContext,
-    ) -> Result<(), Vec<SymbolError>> {
-        let mut populator = SymbolTablePopulator { type_context, table: self };
-
-        let errs = populator.populate_definition_tables(ast);
-        if !errs.is_empty() {
-            return Err(errs);
-        }
-
-        // Walks the AST, matching the ID of an identifier used in some expression to
-        // the corresponding Symbol.
-        let mut resolver = resolver::ScopeResolver::new(self);
-        resolver.resolve(ast);
-
-        Ok(())
-    }
-
-    pub fn lookup_symbol(&self, id: &ItemId) -> Option<&Symbol> {
-        let def = self.id_to_def.get(id)?;
-        self.def_to_symbol.get(def).map(|s| s.as_ref())
-    }
-
-    pub fn lookup_symbol_by_def(&self, def: &DefId) -> Option<&Symbol> {
-        self.def_to_symbol.get(def).map(|s| s.as_ref())
-    }
-
-    #[allow(dead_code)]
-    pub fn debug(&self) {
-        println!("Symbol table:");
-        println!("----------------");
-        for (id, def) in self.id_to_def.iter() {
-            if let Some(symbol) = self.def_to_symbol.get(def) {
-                println!("{} => {}: {}", id, def, symbol);
-            } else {
-                println!("{} => {} <NO SYMBOL FOUND>", id, def);
-            }
-        }
-    }
-
-    /// Register a new mapping of a fully-qualified symbol name (e.g. `Option::Some`)
-    /// to a Symbol, a descriptor of what that name refers to.
-    fn add_symbol(&mut self, id: &ItemId, fqsn: Fqsn, spec: SymbolSpec) {
-        let def_id = self.def_id_store.fresh();
-        let local_name = fqsn.last_elem();
-        let symbol = Rc::new(Symbol { fully_qualified_name: fqsn.clone(), local_name, spec, def_id });
-        self.symbol_trie.insert(&fqsn, def_id);
-        self.id_to_def.insert(*id, def_id);
-        self.def_to_symbol.insert(def_id, symbol);
-    }
-
-    fn populate_single_builtin(&mut self, fqsn: Fqsn, builtin: Builtin) {
-        let def_id = self.def_id_store.fresh();
-        let spec = SymbolSpec::Builtin(builtin);
-        let local_name = fqsn.last_elem();
-        let symbol = Rc::new(Symbol { fully_qualified_name: fqsn.clone(), local_name, spec, def_id });
-
-        self.symbol_trie.insert(&fqsn, def_id);
-        self.def_to_symbol.insert(def_id, symbol);
-    }
-}
-
-#[allow(dead_code)]
-#[derive(Debug, Clone)]
-pub struct Symbol {
-    fully_qualified_name: Fqsn,
-    local_name: Rc<String>,
-    spec: SymbolSpec,
-    def_id: DefId,
-}
-
-impl Symbol {
-    pub fn local_name(&self) -> &str {
-        self.local_name.as_ref()
-    }
-
-    pub fn def_id(&self) -> DefId {
-        self.def_id
-    }
-
-    pub fn spec(&self) -> SymbolSpec {
-        self.spec.clone()
-    }
-}
-
-impl fmt::Display for Symbol {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "<Local name: {}, {}, Spec: {}>", self.local_name(), self.fully_qualified_name, self.spec)
-    }
-}
-
-//TODO - I think I eventually want to draw a distinction between true global items
-//i.e. global vars, and items whose definitions are scoped. Right now there's a sense
-//in which Func, DataConstructor, RecordConstructor, and GlobalBinding are "globals",
-//whereas LocalVarible and FunctionParam have local scope. But right now, they all
-//get put into a common table, and all get DefId's from a common source.
-//
-//It would be good if individual functions could in parallel look up their own
-//local vars without interfering with other lookups. Also some type definitions
-//should be scoped in a similar way.
-//
-//Also it makes sense that non-globals should not use DefId's, particularly not
-//function parameters (even though they are currently assigned).
-#[derive(Debug, Clone)]
-pub enum SymbolSpec {
-    Builtin(Builtin),
-    Func { method: Option<crate::ast::TypeSingletonName> },
-    DataConstructor { tag: u32, type_id: TypeId },
-    RecordConstructor { tag: u32, type_id: TypeId },
-    GlobalBinding, //Only for global variables, not for function-local ones or ones within a `let` scope context
-    LocalVariable,
-    FunctionParam(u8),
-}
-
-impl fmt::Display for SymbolSpec {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        use self::SymbolSpec::*;
-        match self {
-            Builtin(b) => write!(f, "Builtin: {:?}", b),
-            Func { .. } => write!(f, "Func"),
-            DataConstructor { tag, type_id } => write!(f, "DataConstructor(tag: {}, type: {})", tag, type_id),
-            RecordConstructor { type_id, tag, .. } =>
-                write!(f, "RecordConstructor(tag: {})(<members> -> {})", tag, type_id),
-            GlobalBinding => write!(f, "GlobalBinding"),
-            LocalVariable => write!(f, "Local variable"),
-            FunctionParam(n) => write!(f, "Function param: {}", n),
-        }
-    }
-}
--- a/schala-lang/src/symbol_table/populator.rs
+++ b/schala-lang/src/symbol_table/populator.rs
@ -1,352 +0,0 @@
-use std::{
-    collections::{hash_map::Entry, HashMap, HashSet},
-    rc::Rc,
-    str::FromStr,
-};
-
-use super::{Fqsn, NameKind, NameSpec, ScopeSegment, SymbolError, SymbolSpec, SymbolTable, TypeKind};
-use crate::{
-    ast::{
-        Declaration, Expression, ExpressionKind, ItemId, Statement, StatementKind, TypeBody,
-        TypeSingletonName, Variant, VariantKind, AST,
-    },
-    builtin::Builtin,
-    parsing::Location,
-    type_inference::{self, PendingType, TypeBuilder, TypeContext, VariantBuilder},
-};
-
-pub(super) struct SymbolTablePopulator<'a> {
-    pub(super) type_context: &'a mut TypeContext,
-    pub(super) table: &'a mut SymbolTable,
-}
-
-impl<'a> SymbolTablePopulator<'a> {
-    /* note: this adds names for *forward reference* but doesn't actually create any types. solve that problem
-     * later */
-
-    fn add_symbol(&mut self, id: &ItemId, fqsn: Fqsn, spec: SymbolSpec) {
-        self.table.add_symbol(id, fqsn, spec)
-    }
-
-    /// This function traverses the AST and adds symbol table entries for
-    /// constants, functions, types, and modules defined within. This simultaneously
-    /// checks for dupicate definitions (and returns errors if discovered), and sets
-    /// up name tables that will be used by further parts of the compiler
-    pub fn populate_definition_tables(&mut self, ast: &AST) -> Vec<SymbolError> {
-        let mut scope_stack = vec![];
-        self.add_from_scope(ast.statements.as_ref(), &mut scope_stack, false)
-    }
-
-    fn add_from_scope(
-        &mut self,
-        statements: &[Statement<StatementKind>],
-        scope_stack: &mut Vec<ScopeSegment>,
-        function_scope: bool,
-    ) -> Vec<SymbolError> {
-        let mut errors = vec![];
-
-        for statement in statements {
-            let Statement { id, kind, location } = statement;
-            let location = *location;
-            if let Err(err) = self.add_single_statement(id, kind, location, scope_stack, function_scope) {
-                errors.push(err);
-            } else {
-                let decl = match kind {
-                    StatementKind::Declaration(decl) => decl,
-                    _ => continue,
-                };
-                // If there's an error with a name, don't recurse into subscopes of that name
-                let recursive_errs = match decl {
-                    Declaration::FuncDecl(signature, body) => {
-                        let new_scope = ScopeSegment::Name(signature.name.clone());
-                        scope_stack.push(new_scope);
-                        let output = self.add_from_scope(body.as_ref(), scope_stack, true);
-                        scope_stack.pop();
-                        output
-                    }
-                    Declaration::Module { name, items } => {
-                        let new_scope = ScopeSegment::Name(name.clone());
-                        scope_stack.push(new_scope);
-                        let output = self.add_from_scope(items.as_ref(), scope_stack, false);
-                        scope_stack.pop();
-                        output
-                    }
-                    Declaration::TypeDecl { name, body, mutable } => {
-                        let type_fqsn = Fqsn::from_scope_stack(scope_stack, name.name.clone());
-                        self.add_type_members(name, body, mutable, location, type_fqsn)
-                    }
-
-                    Declaration::Impl { type_name, interface_name: _, block } => {
-                        let mut errors = vec![];
-                        let new_scope = ScopeSegment::Name(Rc::new(format!("<impl-block>{}", type_name)));
-                        scope_stack.push(new_scope);
-
-                        for decl_stmt in block.iter() {
-                            let Statement { id, kind, location } = decl_stmt;
-                            let location = *location;
-                            match kind {
-                                decl @ Declaration::FuncDecl(signature, body) => {
-                                    let output =
-                                        self.add_single_declaration(id, decl, location, scope_stack, true);
-                                    if let Err(e) = output {
-                                        errors.push(e);
-                                    };
-                                    let new_scope = ScopeSegment::Name(signature.name.clone());
-                                    scope_stack.push(new_scope);
-                                    let output = self.add_from_scope(body.as_ref(), scope_stack, true);
-                                    scope_stack.pop();
-                                    errors.extend(output.into_iter());
-                                }
-                                _other => errors.push(SymbolError::BadImplBlockEntry),
-                            };
-                        }
-                        scope_stack.pop();
-                        errors
-                    }
-                    _ => vec![],
-                };
-                errors.extend(recursive_errs.into_iter());
-            }
-        }
-
-        errors
-    }
-
-    fn add_single_statement(
-        &mut self,
-        id: &ItemId,
-        kind: &StatementKind,
-        location: Location,
-        scope_stack: &[ScopeSegment],
-        function_scope: bool,
-    ) -> Result<(), SymbolError> {
-        match kind {
-            StatementKind::Declaration(decl) =>
-                self.add_single_declaration(id, decl, location, scope_stack, function_scope),
-            _ => return Ok(()),
-        }
-    }
-
-    fn add_single_declaration(
-        &mut self,
-        id: &ItemId,
-        decl: &Declaration,
-        location: Location,
-        scope_stack: &[ScopeSegment],
-        function_scope: bool,
-    ) -> Result<(), SymbolError> {
-        match decl {
-            Declaration::FuncSig(signature) => {
-                let fq_function = Fqsn::from_scope_stack(scope_stack, signature.name.clone());
-                self.table
-                    .fq_names
-                    .register(fq_function.clone(), NameSpec { location, kind: NameKind::Function })?;
-                self.table
-                    .types
-                    .register(fq_function.clone(), NameSpec { location, kind: TypeKind::Function })?;
-
-                self.add_symbol(id, fq_function, SymbolSpec::Func { method: None });
-            }
-            Declaration::FuncDecl(signature, ..) => {
-                let fn_name = &signature.name;
-                let fq_function = Fqsn::from_scope_stack(scope_stack, fn_name.clone());
-                self.table
-                    .fq_names
-                    .register(fq_function.clone(), NameSpec { location, kind: NameKind::Function })?;
-                self.table
-                    .types
-                    .register(fq_function.clone(), NameSpec { location, kind: TypeKind::Function })?;
-
-                self.add_symbol(id, fq_function, SymbolSpec::Func { method: None });
-            }
-            Declaration::TypeDecl { name, .. } => {
-                let fq_type = Fqsn::from_scope_stack(scope_stack, name.name.clone());
-                self.table.types.register(fq_type, NameSpec { location, kind: TypeKind::Constructor })?;
-            }
-            //TODO handle type aliases
-            Declaration::TypeAlias { .. } => (),
-            Declaration::Binding { name, .. } => {
-                let fq_binding = Fqsn::from_scope_stack(scope_stack, name.clone());
-                self.table
-                    .fq_names
-                    .register(fq_binding.clone(), NameSpec { location, kind: NameKind::Binding })?;
-                if !function_scope {
-                    self.add_symbol(id, fq_binding, SymbolSpec::GlobalBinding);
-                }
-            }
-            //TODO implement interfaces
-            Declaration::Interface { .. } => (),
-            Declaration::Impl { .. } => (),
-            Declaration::Module { name, .. } => {
-                let fq_module = Fqsn::from_scope_stack(scope_stack, name.clone());
-                self.table.fq_names.register(fq_module, NameSpec { location, kind: NameKind::Module })?;
-            }
-            Declaration::Annotation { name, arguments, inner } => {
-                let inner = inner.as_ref();
-                self.add_single_statement(
-                    &inner.id,
-                    &inner.kind,
-                    inner.location,
-                    scope_stack,
-                    function_scope,
-                )?;
-                self.process_annotation(name.as_ref(), arguments.as_slice(), scope_stack, inner)?;
-            }
-        }
-        Ok(())
-    }
-
-    fn process_annotation(
-        &mut self,
-        name: &str,
-        arguments: &[Expression],
-        scope_stack: &[ScopeSegment],
-        inner: &Statement<StatementKind>,
-    ) -> Result<(), SymbolError> {
-        if name == "register_builtin" {
-            if let Statement {
-                id: _,
-                location: _,
-                kind: StatementKind::Declaration(Declaration::FuncDecl(sig, _)),
-            } = inner
-            {
-                let fqsn = Fqsn::from_scope_stack(scope_stack, sig.name.clone());
-                let builtin_name = match arguments {
-                    [Expression { kind: ExpressionKind::Value(qname), .. }]
-                        if qname.components.len() == 1 =>
-                        qname.components[0].clone(),
-                    _ =>
-                        return Err(SymbolError::BadAnnotation {
-                            name: name.to_string(),
-                            msg: "Bad argument for register_builtin".to_string(),
-                        }),
-                };
-
-                let builtin =
-                    Builtin::from_str(builtin_name.as_str()).map_err(|_| SymbolError::BadAnnotation {
-                        name: name.to_string(),
-                        msg: format!("Invalid builtin: {}", builtin_name),
-                    })?;
-
-                self.table.populate_single_builtin(fqsn, builtin);
-                Ok(())
-            } else {
-                Err(SymbolError::BadAnnotation {
-                    name: name.to_string(),
-                    msg: "register_builtin not annotating a function".to_string(),
-                })
-            }
-        } else {
-            Err(SymbolError::UnknownAnnotation { name: name.to_string() })
-        }
-    }
-
-    fn add_type_members(
-        &mut self,
-        type_name: &TypeSingletonName,
-        type_body: &TypeBody,
-        _mutable: &bool,
-        location: Location,
-        type_fqsn: Fqsn,
-    ) -> Vec<SymbolError> {
-        let (variants, immediate_variant) = match type_body {
-            TypeBody::Variants(variants) => (variants.clone(), false),
-            TypeBody::ImmediateRecord { id, fields } => (
-                vec![Variant {
-                    id: *id,
-                    name: type_name.name.clone(),
-                    kind: VariantKind::Record(fields.clone()),
-                }],
-                true,
-            ),
-        };
-
-        // Check for duplicates before registering any types with the TypeContext
-        let mut seen_variants = HashSet::new();
-        let mut errors = vec![];
-
-        for variant in variants.iter() {
-            if seen_variants.contains(&variant.name) {
-                errors.push(SymbolError::DuplicateVariant {
-                    type_fqsn: type_fqsn.clone(),
-                    name: variant.name.as_ref().to_string(),
-                })
-            }
-            seen_variants.insert(variant.name.clone());
-
-            if let VariantKind::Record(ref members) = variant.kind {
-                let mut seen_members = HashMap::new();
-                for (member_name, _) in members.iter() {
-                    match seen_members.entry(member_name.as_ref()) {
-                        Entry::Occupied(o) => {
-                            let location = *o.get();
-                            errors.push(SymbolError::DuplicateRecord {
-                                type_fqsn: type_fqsn.clone(),
-                                location,
-                                record: variant.name.as_ref().to_string(),
-                                member: member_name.as_ref().to_string(),
-                            });
-                        }
-                        //TODO eventually this should track meaningful locations
-                        Entry::Vacant(v) => {
-                            v.insert(location);
-                        }
-                    }
-                }
-            }
-        }
-
-        if !errors.is_empty() {
-            return errors;
-        }
-
-        let mut type_builder = TypeBuilder::new(type_name.name.as_ref());
-
-        let mut variant_name_map = HashMap::new();
-        for variant in variants.iter() {
-            let Variant { name, kind, id } = variant;
-
-            variant_name_map.insert(name.clone(), id);
-
-            let mut variant_builder = VariantBuilder::new(name.as_ref());
-            match kind {
-                VariantKind::UnitStruct => (),
-                VariantKind::TupleStruct(items) =>
-                    for type_identifier in items {
-                        let pending: PendingType = type_identifier.into();
-                        variant_builder.add_member(pending);
-                    },
-                VariantKind::Record(members) =>
-                    for (field_name, type_identifier) in members.iter() {
-                        let pending: PendingType = type_identifier.into();
-                        variant_builder.add_record_member(field_name.as_ref(), pending);
-                    },
-            }
-            type_builder.add_variant(variant_builder);
-        }
-
-        let type_id = self.type_context.register_type(type_builder);
-        let type_definition = self.type_context.lookup_type(&type_id).unwrap();
-
-        // This index is guaranteed to be the correct tag
-        for (index, variant) in type_definition.variants.iter().enumerate() {
-            let id = variant_name_map.get(&variant.name).unwrap();
-            let tag = index as u32;
-            let spec = match &variant.members {
-                type_inference::VariantMembers::Unit => SymbolSpec::DataConstructor { tag, type_id },
-                type_inference::VariantMembers::Tuple(..) => SymbolSpec::DataConstructor { tag, type_id },
-                type_inference::VariantMembers::Record(..) => SymbolSpec::RecordConstructor { tag, type_id },
-            };
-            self.table.add_symbol(id, type_fqsn.extend(&variant.name), spec);
-        }
-
-        if immediate_variant {
-            let variant = &type_definition.variants[0];
-            let id = variant_name_map.get(&variant.name).unwrap();
-            let spec = SymbolSpec::RecordConstructor { tag: 0, type_id };
-            self.table.add_symbol(id, type_fqsn, spec);
-        }
-
-        vec![]
-    }
-}
--- a/schala-lang/src/symbol_table/resolver.rs
+++ b/schala-lang/src/symbol_table/resolver.rs
@ -1,253 +0,0 @@
-use std::rc::Rc;
-
-use crate::{
-    ast::*,
-    symbol_table::{Fqsn, ScopeSegment, SymbolSpec, SymbolTable},
-    util::ScopeStack,
-};
-
-#[derive(Debug)]
-enum NameType {
-    //TODO eventually this needs to support closures
-    Param(u8),
-    LocalVariable(ItemId),
-    LocalFunction(ItemId),
-    Import(Fqsn),
-}
-
-type LexScope<'a> = ScopeStack<'a, Rc<String>, NameType, ScopeType>;
-
-#[derive(Debug)]
-enum ScopeType {
-    Function { name: Rc<String> },
-    Lambda,
-    PatternMatch,
-    ImplBlock,
-    //TODO add some notion of a let-like scope?
-}
-
-pub struct ScopeResolver<'a> {
-    symbol_table: &'a mut super::SymbolTable,
-    lexical_scopes: LexScope<'a>,
-}
-
-impl<'a> ScopeResolver<'a> {
-    pub fn new(symbol_table: &'a mut SymbolTable) -> Self {
-        let lexical_scopes = ScopeStack::new(None);
-        Self { symbol_table, lexical_scopes }
-    }
-
-    pub fn resolve(&mut self, ast: &AST) {
-        walk_ast(self, ast);
-    }
-
-    /// This method correctly modifies the id_to_def table (ItemId) to have the appropriate
-    /// mappings.
-    fn lookup_name_in_scope(&mut self, name: &QualifiedName) {
-        //TODO this method badly needs attention
-        let QualifiedName { id, components } = name;
-
-        let local_name = components.first().unwrap().clone();
-        let name_type = self.lexical_scopes.lookup(&local_name);
-        let fqsn = Fqsn { scopes: components.iter().map(|name| ScopeSegment::Name(name.clone())).collect() };
-        let def_id = self.symbol_table.symbol_trie.lookup(&fqsn);
-
-        //TODO handle a "partial" qualified name, and also handle it down in the pattern-matching
-        //section
-        if components.len() == 1 {
-            match name_type {
-                Some(NameType::Import(fqsn)) => {
-                    let def_id = self.symbol_table.symbol_trie.lookup(fqsn);
-
-                    if let Some(def_id) = def_id {
-                        self.symbol_table.id_to_def.insert(*id, def_id);
-                    }
-                }
-                Some(NameType::Param(n)) => {
-                    let spec = SymbolSpec::FunctionParam(*n);
-                    //TODO need to come up with a better solution for local variable FQSNs
-                    let lscope = ScopeSegment::Name(Rc::new("<local-param>".to_string()));
-                    let fqsn = Fqsn { scopes: vec![lscope, ScopeSegment::Name(local_name.clone())] };
-                    self.symbol_table.add_symbol(id, fqsn, spec);
-                }
-                Some(NameType::LocalFunction(item_id)) => {
-                    let def_id = self.symbol_table.id_to_def.get(item_id);
-                    if let Some(def_id) = def_id {
-                        let def_id = *def_id;
-                        self.symbol_table.id_to_def.insert(*id, def_id);
-                    }
-                }
-                Some(NameType::LocalVariable(item_id)) => {
-                    let def_id = self.symbol_table.id_to_def.get(item_id);
-                    if let Some(def_id) = def_id {
-                        let def_id = *def_id;
-                        self.symbol_table.id_to_def.insert(*id, def_id);
-                    }
-                }
-                None =>
-                    if let Some(def_id) = def_id {
-                        self.symbol_table.id_to_def.insert(*id, def_id);
-                    },
-            }
-        } else if let Some(def_id) = def_id {
-            self.symbol_table.id_to_def.insert(*id, def_id);
-        }
-    }
-}
-
-impl<'a> ASTVisitor for ScopeResolver<'a> {
-    // Import statements bring in a bunch of local names that all map to a specific FQSN.
-    // FQSNs map to a Symbol (or this is an error), Symbols have a DefId. So for every
-    // name we import, we map a local name (a string) to a NameType::ImportedDefinition(DefId).
-    fn import(&mut self, import_spec: &ImportSpecifier) -> Recursion {
-        let ImportSpecifier { ref path_components, ref imported_names, .. } = &import_spec;
-        match imported_names {
-            ImportedNames::All => {
-                let prefix =
-                    Fqsn { scopes: path_components.iter().map(|c| ScopeSegment::Name(c.clone())).collect() };
-                let members = self.symbol_table.symbol_trie.get_children(&prefix);
-                for fqsn in members.into_iter() {
-                    self.lexical_scopes.insert(fqsn.last_elem(), NameType::Import(fqsn));
-                }
-            }
-            ImportedNames::LastOfPath => {
-                let fqsn =
-                    Fqsn { scopes: path_components.iter().map(|c| ScopeSegment::Name(c.clone())).collect() };
-                self.lexical_scopes.insert(fqsn.last_elem(), NameType::Import(fqsn));
-            }
-            ImportedNames::List(ref names) => {
-                let fqsn_prefix: Vec<ScopeSegment> =
-                    path_components.iter().map(|c| ScopeSegment::Name(c.clone())).collect();
-                for name in names.iter() {
-                    let mut scopes = fqsn_prefix.clone();
-                    scopes.push(ScopeSegment::Name(name.clone()));
-                    let fqsn = Fqsn { scopes };
-                    self.lexical_scopes.insert(fqsn.last_elem(), NameType::Import(fqsn));
-                }
-            }
-        };
-        Recursion::Continue
-    }
-
-    fn declaration(&mut self, declaration: &Declaration, id: &ItemId) -> Recursion {
-        let cur_function_name = match self.lexical_scopes.get_name() {
-            //TODO this needs to be a fqsn
-            Some(ScopeType::Function { name }) => Some(name.clone()),
-            _ => None,
-        };
-        match declaration {
-            Declaration::FuncDecl(signature, block) => {
-                let param_names = signature.params.iter().map(|param| param.name.clone());
-                //TODO I'm 90% sure this is right, until I get to closures
-                //let mut new_scope = self.lexical_scopes.new_scope(Some(ScopeType::Function { name: signature.name.clone() }));
-                //TODO this will recurse unwantedly into scopes; need to pop an outer function
-                //scope off first before going into a non-closure scope
-                let mut new_scope =
-                    ScopeStack::new(Some(ScopeType::Function { name: signature.name.clone() }));
-
-                for (n, param) in param_names.enumerate() {
-                    new_scope.insert(param, NameType::Param(n as u8));
-                }
-
-                self.lexical_scopes.insert(signature.name.clone(), NameType::LocalFunction(*id));
-
-                let mut new_resolver =
-                    ScopeResolver { symbol_table: self.symbol_table, lexical_scopes: new_scope };
-                walk_block(&mut new_resolver, block);
-                Recursion::Stop
-            }
-            Declaration::Binding { name, .. } => {
-                if let Some(fn_name) = cur_function_name {
-                    // We are within a function scope
-                    let fqsn =
-                        Fqsn { scopes: vec![ScopeSegment::Name(fn_name), ScopeSegment::Name(name.clone())] };
-                    self.symbol_table.add_symbol(id, fqsn, SymbolSpec::LocalVariable);
-                    self.lexical_scopes.insert(name.clone(), NameType::LocalVariable(*id));
-                }
-                Recursion::Continue
-            }
-            Declaration::Impl { block, .. } => {
-                let new_scope = ScopeStack::new(Some(ScopeType::ImplBlock));
-                let mut new_resolver =
-                    ScopeResolver { symbol_table: self.symbol_table, lexical_scopes: new_scope };
-                for stmt in block.iter() {
-                    walk_declaration(&mut new_resolver, &stmt.kind, &stmt.id);
-                }
-                Recursion::Stop
-            }
-            _ => Recursion::Continue,
-        }
-    }
-
-    fn expression(&mut self, expression: &Expression) -> Recursion {
-        use ExpressionKind::*;
-        match &expression.kind {
-            Value(name) => {
-                self.lookup_name_in_scope(name);
-            }
-            NamedStruct { name, fields: _ } => {
-                self.lookup_name_in_scope(name);
-            }
-            Lambda { params, body, .. } => {
-                let param_names = params.iter().map(|param| param.name.clone());
-                //TODO need to properly handle closure scope, this is currently broken
-                //let mut new_scope = self.lexical_scopes.new_scope(Some(ScopeType::Function { name: signature.name.clone() }));
-                let mut new_scope = ScopeStack::new(Some(ScopeType::Lambda));
-
-                for (n, param) in param_names.enumerate() {
-                    new_scope.insert(param, NameType::Param(n as u8));
-                }
-
-                let mut new_resolver =
-                    ScopeResolver { symbol_table: self.symbol_table, lexical_scopes: new_scope };
-                walk_block(&mut new_resolver, body);
-                return Recursion::Stop;
-            }
-            IfExpression { discriminator, body } => {
-                if let Some(d) = discriminator.as_ref() {
-                    walk_expression(self, d);
-                }
-                let mut resolver = ScopeResolver {
-                    lexical_scopes: self.lexical_scopes.new_scope(Some(ScopeType::PatternMatch)),
-                    symbol_table: self.symbol_table,
-                };
-                walk_if_expr_body(&mut resolver, body);
-                return Recursion::Stop;
-            }
-            _ => (),
-        }
-        Recursion::Continue
-    }
-
-    fn pattern(&mut self, pat: &Pattern) -> Recursion {
-        use Pattern::*;
-
-        match pat {
-            Literal(..) | Ignored | TuplePattern(..) => (),
-            TupleStruct(name, _) | Record(name, _) => {
-                self.lookup_name_in_scope(name);
-            }
-            //TODO this isn't really the right syntax for a VarOrName
-            VarOrName(QualifiedName { id, components }) => {
-                if components.len() == 1 {
-                    //TODO need a better way to construct a FQSN from a QualifiedName
-                    let local_name: Rc<String> = components[0].clone();
-                    let lscope = ScopeSegment::Name(Rc::new("<local-case-match>".to_string()));
-                    let fqsn = Fqsn { scopes: vec![lscope, ScopeSegment::Name(local_name.clone())] };
-                    self.symbol_table.add_symbol(id, fqsn, SymbolSpec::LocalVariable);
-                    self.lexical_scopes.insert(local_name, NameType::LocalVariable(*id));
-                } else {
-                    let fqsn = Fqsn {
-                        scopes: components.iter().map(|name| ScopeSegment::Name(name.clone())).collect(),
-                    };
-                    let def_id = self.symbol_table.symbol_trie.lookup(&fqsn);
-
-                    if let Some(def_id) = def_id {
-                        self.symbol_table.id_to_def.insert(*id, def_id);
-                    }
-                }
-            }
-        };
-        Recursion::Continue
-    }
-}
--- a/schala-lang/src/symbol_table/symbol_trie.rs
+++ b/schala-lang/src/symbol_table/symbol_trie.rs
@ -1,70 +0,0 @@
-use std::{
-    collections::hash_map::DefaultHasher,
-    hash::{Hash, Hasher},
-};
-
-use radix_trie::{Trie, TrieCommon, TrieKey};
-
-use super::{DefId, Fqsn, ScopeSegment};
-
-#[derive(Debug)]
-pub struct SymbolTrie(Trie<Fqsn, DefId>);
-
-impl TrieKey for Fqsn {
-    fn encode_bytes(&self) -> Vec<u8> {
-        let mut hasher = DefaultHasher::new();
-        let mut output = vec![];
-        for segment in self.scopes.iter() {
-            let ScopeSegment::Name(s) = segment;
-            s.as_bytes().hash(&mut hasher);
-            output.extend_from_slice(&hasher.finish().to_be_bytes());
-        }
-        output
-    }
-}
-
-impl SymbolTrie {
-    pub fn new() -> SymbolTrie {
-        SymbolTrie(Trie::new())
-    }
-
-    pub fn insert(&mut self, fqsn: &Fqsn, def_id: DefId) {
-        self.0.insert(fqsn.clone(), def_id);
-    }
-
-    pub fn lookup(&self, fqsn: &Fqsn) -> Option<DefId> {
-        self.0.get(fqsn).cloned()
-    }
-
-    pub fn get_children(&self, fqsn: &Fqsn) -> Vec<Fqsn> {
-        let subtrie = match self.0.subtrie(fqsn) {
-            Some(s) => s,
-            None => return vec![],
-        };
-        let output: Vec<Fqsn> = subtrie.keys().filter(|cur_key| **cur_key != *fqsn).cloned().collect();
-        output
-    }
-}
-
-#[cfg(test)]
-mod test {
-    use super::*;
-    use crate::symbol_table::Fqsn;
-
-    fn make_fqsn(strs: &[&str]) -> Fqsn {
-        Fqsn::from_strs(strs)
-    }
-
-    #[test]
-    fn test_trie_insertion() {
-        let id = DefId::default();
-        let mut trie = SymbolTrie::new();
-
-        trie.insert(&make_fqsn(&["unrelated", "thing"]), id);
-        trie.insert(&make_fqsn(&["outer", "inner"]), id);
-        trie.insert(&make_fqsn(&["outer", "inner", "still_inner"]), id);
-
-        let children = trie.get_children(&make_fqsn(&["outer", "inner"]));
-        assert_eq!(children.len(), 1);
-    }
-}
--- a/schala-lang/src/symbol_table/test.rs
+++ b/schala-lang/src/symbol_table/test.rs
@ -1,314 +0,0 @@
-#![cfg(test)]
-use assert_matches::assert_matches;
-
-use super::*;
-use crate::util::quick_ast;
-
-fn add_symbols(src: &str) -> (SymbolTable, Result<(), Vec<SymbolError>>) {
-    let ast = quick_ast(src);
-    let mut symbol_table = SymbolTable::new();
-    let mut type_context = crate::type_inference::TypeContext::new();
-    let result = symbol_table.process_ast(&ast, &mut type_context);
-    (symbol_table, result)
-}
-
-fn make_fqsn(strs: &[&str]) -> Fqsn {
-    Fqsn::from_strs(strs)
-}
-
-#[test]
-fn basic_symbol_table() {
-    let src = "let a = 10; fn b() { 20 }";
-    let (symbols, _) = add_symbols(src);
-
-    fn make_fqsn(strs: &[&str]) -> Fqsn {
-        Fqsn::from_strs(strs)
-    }
-
-    symbols.fq_names.table.get(&make_fqsn(&["b"])).unwrap();
-
-    let src = "type Option<T> = Some(T) | None";
-    let (symbols, _) = add_symbols(src);
-
-    symbols.types.table.get(&make_fqsn(&["Option"])).unwrap();
-}
-
-#[test]
-fn no_function_definition_duplicates() {
-    let source = r#"
-  fn a() { 1 }
-  fn b() { 2 }
-  fn a() { 3 }
-  "#;
-    let (_, output) = add_symbols(source);
-    let errs = output.unwrap_err();
-    assert_matches!(&errs[..], [
-      SymbolError::DuplicateName { prev_name, ..}
-    ] if prev_name == &Fqsn::from_strs(&["a"])
-    );
-}
-
-#[test]
-fn no_variable_definition_duplicates() {
-    let source = r#"
-  let x = 9
-  let a = 20
-  let q = 39
-  let a = 30
-  let x = 34
-  "#;
-    let (_, output) = add_symbols(source);
-    let errs = output.unwrap_err();
-
-    assert_matches!(&errs[..], [
-      SymbolError::DuplicateName { prev_name: pn1, ..},
-      SymbolError::DuplicateName { prev_name: pn2, ..}
-    ] if pn1 == &Fqsn::from_strs(&["a"]) && pn2 == &Fqsn::from_strs(&["x"])
-    );
-}
-
-#[test]
-fn no_type_definition_duplicates() {
-    let source = r#"
-  let x = 9
-  type Food = Japchae | Burrito | Other
-  type Food = GoodJapchae | Breadfruit
-  "#;
-    let (_, output) = add_symbols(source);
-    let errs = output.unwrap_err();
-    let err = &errs[0];
-
-    match err {
-        SymbolError::DuplicateName { location: _, prev_name } => {
-            assert_eq!(prev_name, &Fqsn::from_strs(&["Food"]));
-
-            //TODO restore this Location test
-            //assert_eq!(location, &Location { line_num: 2, char_num: 2 });
-        }
-        _ => panic!(),
-    }
-}
-
-#[test]
-fn no_variant_duplicates() {
-    let source = r#"
-type Panda = FoolsGold | Kappa(i32) | Remix | Kappa | Thursday | Remix
-"#;
-    let (_, output) = add_symbols(source);
-    let errs = output.unwrap_err();
-    assert_eq!(errs.len(), 2);
-    assert_matches!(&errs[0], SymbolError::DuplicateVariant {
-        type_fqsn, name } if *type_fqsn == Fqsn::from_strs(&["Panda"]) &&
-        name == "Kappa");
-
-    assert_matches!(&errs[1], SymbolError::DuplicateVariant {
-        type_fqsn, name } if *type_fqsn == Fqsn::from_strs(&["Panda"]) &&
-        name == "Remix");
-}
-
-#[test]
-fn no_variable_definition_duplicates_in_function() {
-    let source = r#"
-  fn a() {
-    let a = 20
-    let b = 40
-    a + b
-  }
-
-  fn q() {
-    let a = 29
-    let x = 30
-    let x = 33
-  }
-  "#;
-    let (_, output) = add_symbols(source);
-    let errs = output.unwrap_err();
-    assert_matches!(&errs[..], [
-      SymbolError::DuplicateName { prev_name: pn1, ..},
-    ] if pn1 == &Fqsn::from_strs(&["q", "x"])
-    );
-}
-
-#[test]
-fn dont_falsely_detect_duplicates() {
-    let source = r#"
-  let a = 20;
-  fn some_func() {
-    let a = 40;
-    77
-  }
-  let q = 39
-  "#;
-    let (symbols, _) = add_symbols(source);
-
-    assert!(symbols.fq_names.table.get(&make_fqsn(&["a"])).is_some());
-    assert!(symbols.fq_names.table.get(&make_fqsn(&["some_func", "a"])).is_some());
-}
-
-#[test]
-fn enclosing_scopes() {
-    let source = r#"
-fn outer_func(x) {
-fn inner_func(arg) {
-  arg
-}
-x + inner_func(x)
-}"#;
-    let (symbols, _) = add_symbols(source);
-    assert!(symbols.fq_names.table.get(&make_fqsn(&["outer_func"])).is_some());
-    assert!(symbols.fq_names.table.get(&make_fqsn(&["outer_func", "inner_func"])).is_some());
-}
-
-#[test]
-fn enclosing_scopes_2() {
-    let source = r#"
-fn outer_func(x) {
-fn inner_func(arg) {
-  arg
-}
-
-fn second_inner_func() {
-  fn another_inner_func() {
-  }
-}
-
-inner_func(x)
-}
-"#;
-    let (symbols, _) = add_symbols(source);
-    assert!(symbols.fq_names.table.get(&make_fqsn(&["outer_func"])).is_some());
-    assert!(symbols.fq_names.table.get(&make_fqsn(&["outer_func", "inner_func"])).is_some());
-    assert!(symbols.fq_names.table.get(&make_fqsn(&["outer_func", "second_inner_func"])).is_some());
-    assert!(symbols
-        .fq_names
-        .table
-        .get(&make_fqsn(&["outer_func", "second_inner_func", "another_inner_func"]))
-        .is_some());
-}
-
-#[test]
-fn enclosing_scopes_3() {
-    let source = r#"
-fn outer_func(x) {
-
- fn inner_func(arg) {
-  arg
-}
-
-fn second_inner_func() {
-  fn another_inner_func() {
-  }
-  fn another_inner_func() {
-  }
-}
-
-inner_func(x)
-}"#;
-    let (_, output) = add_symbols(source);
-    let _err = output.unwrap_err();
-}
-
-#[test]
-fn modules() {
-    let source = r#"
-module stuff {
-  fn item() {
-  }
-}
-
-fn item()
-"#;
-
-    let (symbols, _) = add_symbols(source);
-    symbols.fq_names.table.get(&make_fqsn(&["stuff"])).unwrap();
-    symbols.fq_names.table.get(&make_fqsn(&["item"])).unwrap();
-    symbols.fq_names.table.get(&make_fqsn(&["stuff", "item"])).unwrap();
-}
-
-#[test]
-fn duplicate_modules() {
-    let source = r#"
-    module q {
-      fn foo() { 4 }
-    }
-
-    module a {
-      fn foo() { 334 }
-    }
-
-    module a {
-      fn sarat() { 39 }
-      fn foo() { 256.1 }
-    }
-    "#;
-    let (_, output) = add_symbols(source);
-    let errs = output.unwrap_err();
-
-    assert_matches!(&errs[..], [
-      SymbolError::DuplicateName { prev_name: pn1, ..},
-    ] if pn1 == &Fqsn::from_strs(&["a"])
-    );
-}
-
-#[test]
-fn duplicate_struct_members() {
-    let source = r#"
-      type Tarak = Tarak {
-        loujet: i32
-        ,
-        mets: i32,
-        mets: i32
-        ,
-      }
-    "#;
-
-    let (_, output) = add_symbols(source);
-    let errs = dbg!(output.unwrap_err());
-    assert_matches!(&errs[..], [
-      SymbolError::DuplicateRecord {
-        type_fqsn, member, record, ..},
-    ] if type_fqsn == &Fqsn::from_strs(&["Tarak"]) && member == "mets" && record == "Tarak"
-    );
-}
-
-#[test]
-fn method_definition_added_to_symbol_table() {
-    let source = r#"
-
-type Foo = { x: Int, y: Int }
-
-impl Foo {
-    fn hella() {
-        let a = 50
-        self.x + a
-    }
-}
-"#;
-    let (symbols, _) = add_symbols(source);
-    symbols.debug();
-    assert!(symbols.fq_names.table.get(&make_fqsn(&["<impl-block>Foo", "hella"])).is_some());
-    assert!(symbols.fq_names.table.get(&make_fqsn(&["<impl-block>Foo", "hella", "a"])).is_some());
-}
-
-#[test]
-fn duplicate_method_definitions_detected() {
-    let source = r#"
-
-type Foo = { x: Int, y: Int }
-
-impl Foo {
-    fn hella() {
-        self.x + 50
-    }
-
-    fn hella() {
-        self.x + 40
-    }
-}
-"#;
-    let (_symbols, output) = add_symbols(source);
-    let errs = output.unwrap_err();
-    assert_matches!(&errs[..], [
-      SymbolError::DuplicateName { prev_name: pn1, ..},
-    ] if pn1 == &Fqsn::from_strs(&["<impl-block>Foo", "hella"]));
-}
--- a/schala-lang/src/tree_walk_eval/evaluator.rs
+++ b/schala-lang/src/tree_walk_eval/evaluator.rs
@ -1,513 +0,0 @@
-use std::rc::Rc;
-
-use super::{EvalResult, Memory, MemoryValue, Primitive, State};
-use crate::{
-    builtin::Builtin,
-    reduced_ir::{
-        Alternative, Callable, Expression, FunctionDefinition, Literal, Lookup, Pattern, ReducedIR, Statement,
-    },
-    type_inference::TypeContext,
-    util::ScopeStack,
-};
-
-#[derive(Debug)]
-enum StatementOutput {
-    Primitive(Primitive),
-    Nothing,
-}
-
-#[derive(Debug, Clone, Copy)]
-enum LoopControlFlow {
-    Break,
-    Continue,
-}
-
-pub struct Evaluator<'a, 'b> {
-    type_context: &'b TypeContext,
-    state: &'b mut State<'a>,
-    early_returning: bool,
-    loop_control: Option<LoopControlFlow>,
-}
-
-impl<'a, 'b> Evaluator<'a, 'b> {
-    pub(crate) fn new(state: &'b mut State<'a>, type_context: &'b TypeContext) -> Self {
-        Self { state, type_context, early_returning: false, loop_control: None }
-    }
-
-    pub fn evaluate(&mut self, reduced: ReducedIR, repl: bool) -> Vec<Result<String, String>> {
-        let mut acc = vec![];
-        for (def_id, function) in reduced.functions.into_iter() {
-            let mem = (&def_id).into();
-            self.state.memory.insert(mem, MemoryValue::Function(function));
-        }
-
-        for statement in reduced.entrypoint.into_iter() {
-            match self.statement(statement) {
-                Ok(StatementOutput::Primitive(output)) if repl =>
-                    acc.push(Ok(output.to_repl(self.type_context))),
-                Ok(_) => (),
-                Err(error) => {
-                    acc.push(Err(error.msg));
-                    return acc;
-                }
-            }
-        }
-        acc
-    }
-
-    fn block(&mut self, statements: Vec<Statement>) -> EvalResult<Primitive> {
-        let mut retval = None;
-        for stmt in statements.into_iter() {
-            match self.statement(stmt)? {
-                StatementOutput::Nothing => (),
-                StatementOutput::Primitive(prim) => {
-                    retval = Some(prim);
-                }
-            };
-            if self.early_returning {
-                break;
-            }
-            if self.loop_control.is_some() {
-                break;
-            }
-        }
-        Ok(if let Some(ret) = retval { ret } else { self.expression(Expression::unit())? })
-    }
-
-    fn statement(&mut self, stmt: Statement) -> EvalResult<StatementOutput> {
-        match stmt {
-            Statement::Binding { ref id, expr, constant: _ } => {
-                let evaluated = self.expression(expr)?;
-                self.state.memory.insert(id.into(), evaluated.into());
-                Ok(StatementOutput::Nothing)
-            }
-            Statement::Expression(expr) => {
-                let evaluated = self.expression(expr)?;
-                Ok(StatementOutput::Primitive(evaluated))
-            }
-            Statement::Return(expr) => {
-                let evaluated = self.expression(expr)?;
-                self.early_returning = true;
-                Ok(StatementOutput::Primitive(evaluated))
-            }
-            Statement::Break => {
-                self.loop_control = Some(LoopControlFlow::Break);
-                Ok(StatementOutput::Nothing)
-            }
-            Statement::Continue => {
-                self.loop_control = Some(LoopControlFlow::Continue);
-                Ok(StatementOutput::Nothing)
-            }
-        }
-    }
-
-    fn expression(&mut self, expression: Expression) -> EvalResult<Primitive> {
-        Ok(match expression {
-            Expression::Literal(lit) => Primitive::Literal(lit),
-            Expression::Tuple(items) => Primitive::Tuple(
-                items
-                    .into_iter()
-                    .map(|expr| self.expression(expr))
-                    .collect::<EvalResult<Vec<Primitive>>>()?,
-            ),
-            Expression::List(items) => Primitive::List(
-                items
-                    .into_iter()
-                    .map(|expr| self.expression(expr))
-                    .collect::<EvalResult<Vec<Primitive>>>()?,
-            ),
-            Expression::Lookup(kind) => match kind {
-                Lookup::Function(ref id) => {
-                    let mem = id.into();
-                    match self.state.memory.lookup(&mem) {
-                        // This just checks that the function exists in "memory" by ID, we don't
-                        // actually retrieve it until `apply_function()`
-                        Some(MemoryValue::Function(_)) => Primitive::Callable(Callable::UserDefined(*id)),
-                        x => return Err(format!("Function not found for id: {} : {:?}", id, x).into()),
-                    }
-                }
-                Lookup::Param(n) => {
-                    let mem = n.into();
-                    match self.state.memory.lookup(&mem) {
-                        Some(MemoryValue::Primitive(prim)) => prim.clone(),
-                        e => return Err(format!("Param lookup error, got {:?}", e).into()),
-                    }
-                }
-                Lookup::SelfParam => {
-                    let mem = Memory::self_param();
-                    match self.state.memory.lookup(&mem) {
-                        Some(MemoryValue::Primitive(prim)) => prim.clone(),
-                        e => return Err(format!("SelfParam lookup error, got {:?}", e).into()),
-                    }
-                }
-                Lookup::LocalVar(ref id) | Lookup::GlobalVar(ref id) => {
-                    let mem = id.into();
-                    match self.state.memory.lookup(&mem) {
-                        Some(MemoryValue::Primitive(expr)) => expr.clone(),
-                        _ =>
-                            return Err(
-                                format!("Nothing found for local/gloval variable lookup {}", id).into()
-                            ),
-                    }
-                }
-            },
-            Expression::Assign { ref lval, box rval } => {
-                let mem = lval.into();
-                let evaluated = self.expression(rval)?;
-                println!("Inserting {:?} into {:?}", evaluated, mem);
-                self.state.memory.insert(mem, MemoryValue::Primitive(evaluated));
-                Primitive::unit()
-            }
-            Expression::Call { box f, args } => self.call_expression(f, args, None)?,
-            Expression::CallMethod { box f, args, box self_expr } =>
-                self.call_expression(f, args, Some(self_expr))?,
-            Expression::Callable(Callable::DataConstructor { type_id, tag }) => {
-                let arity = self.type_context.lookup_variant_arity(&type_id, tag).unwrap();
-                if arity == 0 {
-                    Primitive::Object { type_id, tag, items: vec![], ordered_fields: None }
-                } else {
-                    Primitive::Callable(Callable::DataConstructor { type_id, tag })
-                }
-            }
-            Expression::Callable(func) => Primitive::Callable(func),
-            Expression::Conditional { box cond, then_clause, else_clause } => {
-                let cond = self.expression(cond)?;
-                match cond {
-                    Primitive::Literal(Literal::Bool(true)) => self.block(then_clause)?,
-                    Primitive::Literal(Literal::Bool(false)) => self.block(else_clause)?,
-                    v => return Err(format!("Non-boolean value {:?} in if-statement", v).into()),
-                }
-            }
-            Expression::CaseMatch { box cond, alternatives } =>
-                self.case_match_expression(cond, alternatives)?,
-            Expression::Index { box indexee, box indexer } => {
-                let indexee = self.expression(indexee)?;
-                let indexer = self.expression(indexer)?;
-                match (indexee, indexer) {
-                    (Primitive::List(items), Primitive::Literal(Literal::Nat(n))) =>
-                        match items.get(n as usize) {
-                            Some(item) => item.clone(),
-                            None => return Err(format!("Invalid index {} for this value", n).into()),
-                        },
-                    _ => return Err("Invalid index type".to_string().into()),
-                }
-            }
-            Expression::Loop { box cond, statements } => self.loop_expression(cond, statements)?,
-            Expression::ReductionError(e) => return Err(e.into()),
-            Expression::Access { name, box expr } => {
-                let expr = self.expression(expr)?;
-                match expr {
-                    Primitive::Object { items, ordered_fields: Some(ordered_fields), .. } => {
-                        let idx = match ordered_fields.iter().position(|s| s == &name) {
-                            Some(idx) => idx,
-                            None => return Err(format!("Field `{}` not found", name).into()),
-                        };
-
-                        let item = match items.get(idx) {
-                            Some(item) => item,
-                            None => return Err(format!("Field lookup `{}` failed", name).into()),
-                        };
-
-                        item.clone()
-                    }
-                    e =>
-                        return Err(
-                            format!("Trying to do a field lookup on a non-object value: {:?}", e).into()
-                        ),
-                }
-            }
-        })
-    }
-
-    fn loop_expression(&mut self, cond: Expression, statements: Vec<Statement>) -> EvalResult<Primitive> {
-        let existing = self.loop_control;
-        let output = self.loop_expression_inner(cond, statements);
-        self.loop_control = existing;
-        output
-    }
-
-    fn loop_expression_inner(
-        &mut self,
-        cond: Expression,
-        statements: Vec<Statement>,
-    ) -> EvalResult<Primitive> {
-        loop {
-            let cond = self.expression(cond.clone())?;
-            println!("COND: {:?}", cond);
-            match cond {
-                Primitive::Literal(Literal::Bool(true)) => (),
-                Primitive::Literal(Literal::Bool(false)) => break,
-                e => return Err(format!("Loop condition evaluates to non-boolean: {:?}", e).into()),
-            };
-            //TODO eventually loops shoudl be able to return something
-            let _output = self.block(statements.clone())?;
-            match self.loop_control {
-                None => (),
-                Some(LoopControlFlow::Continue) => {
-                    self.loop_control = None;
-                }
-                Some(LoopControlFlow::Break) => {
-                    break;
-                }
-            }
-        }
-        Ok(Primitive::unit())
-    }
-
-    fn case_match_expression(
-        &mut self,
-        cond: Expression,
-        alternatives: Vec<Alternative>,
-    ) -> EvalResult<Primitive> {
-        fn matches(scrut: &Primitive, pat: &Pattern, scope: &mut ScopeStack<Memory, MemoryValue>) -> bool {
-            match pat {
-                Pattern::Ignored => true,
-                Pattern::Binding(ref def_id) => {
-                    let mem = def_id.into();
-                    scope.insert(mem, MemoryValue::Primitive(scrut.clone())); //TODO make sure this doesn't cause problems with nesting
-                    true
-                }
-                Pattern::Literal(pat_literal) =>
-                    if let Primitive::Literal(scrut_literal) = scrut {
-                        pat_literal == scrut_literal
-                    } else {
-                        false
-                    },
-                Pattern::Tuple { subpatterns, tag } => match tag {
-                    None => match scrut {
-                        Primitive::Tuple(items) if items.len() == subpatterns.len() => items
-                            .iter()
-                            .zip(subpatterns.iter())
-                            .all(|(item, subpat)| matches(item, subpat, scope)),
-                        _ => false, //TODO should be a type error
-                    },
-                    Some(pattern_tag) => match scrut {
-                        //TODO should test type_ids for runtime type checking, once those work
-                        Primitive::Object { tag, items, .. }
-                            if tag == pattern_tag && items.len() == subpatterns.len() =>
-                            items
-                                .iter()
-                                .zip(subpatterns.iter())
-                                .all(|(item, subpat)| matches(item, subpat, scope)),
-                        _ => false,
-                    },
-                },
-                Pattern::Record { tag: pattern_tag, subpatterns } => match scrut {
-                    //TODO several types of possible error here
-                    Primitive::Object { tag, items, ordered_fields: Some(ordered_fields), .. }
-                        if tag == pattern_tag =>
-                        subpatterns.iter().all(|(field_name, subpat)| {
-                            let idx = ordered_fields
-                                .iter()
-                                .position(|field| field.as_str() == field_name.as_ref())
-                                .unwrap();
-                            let item = &items[idx];
-                            matches(item, subpat, scope)
-                        }),
-                    _ => false,
-                },
-            }
-        }
-        let cond = self.expression(cond)?;
-
-        for alt in alternatives.into_iter() {
-            let mut new_scope = self.state.memory.new_scope(None);
-            if matches(&cond, &alt.pattern, &mut new_scope) {
-                let mut new_state = State { memory: new_scope };
-                let mut evaluator = Evaluator::new(&mut new_state, self.type_context);
-                let output = evaluator.block(alt.item);
-                self.early_returning = evaluator.early_returning;
-                return output;
-            }
-        }
-        Err("No valid match in match expression".into())
-    }
-
-    //TODO need to do something with self_expr to make method invocations actually work
-    fn call_expression(
-        &mut self,
-        f: Expression,
-        args: Vec<Expression>,
-        self_expr: Option<Expression>,
-    ) -> EvalResult<Primitive> {
-        let func = match self.expression(f)? {
-            Primitive::Callable(func) => func,
-            other => return Err(format!("Trying to call non-function value: {:?}", other).into()),
-        };
-        match func {
-            Callable::Builtin(builtin) => self.apply_builtin(builtin, args),
-            Callable::UserDefined(def_id) => {
-                let mem = (&def_id).into();
-                match self.state.memory.lookup(&mem) {
-                    Some(MemoryValue::Function(FunctionDefinition { body })) => {
-                        let body = body.clone(); //TODO ideally this clone would not happen
-                        self.apply_function(body, args, self_expr)
-                    }
-                    e => Err(format!("Error looking up function with id {}: {:?}", def_id, e).into()),
-                }
-            }
-            Callable::Lambda { arity, body } => {
-                if arity as usize != args.len() {
-                    return Err(format!(
-                        "Lambda expression requries {} arguments, only {} provided",
-                        arity,
-                        args.len()
-                    )
-                    .into());
-                }
-                self.apply_function(body, args, None)
-            }
-            Callable::DataConstructor { type_id, tag } => {
-                let arity = self.type_context.lookup_variant_arity(&type_id, tag).unwrap();
-                if arity as usize != args.len() {
-                    return Err(format!(
-                        "Constructor expression requries {} arguments, only {} provided",
-                        arity,
-                        args.len()
-                    )
-                    .into());
-                }
-
-                let mut items: Vec<Primitive> = vec![];
-                for arg in args.into_iter() {
-                    items.push(self.expression(arg)?);
-                }
-                Ok(Primitive::Object { type_id, tag, items, ordered_fields: None })
-            }
-            Callable::RecordConstructor { type_id, tag, field_order } => {
-                //TODO maybe I'll want to do a runtime check of the evaluated fields
-                /*
-                let record_members = self.type_context.lookup_record_members(type_id, tag)
-                    .ok_or(format!("Runtime record lookup for: {} {} not found", type_id, tag).into())?;
-                */
-
-                let mut items: Vec<Primitive> = vec![];
-                for arg in args.into_iter() {
-                    items.push(self.expression(arg)?);
-                }
-                Ok(Primitive::Object { type_id, tag, items, ordered_fields: Some(field_order) })
-            }
-        }
-    }
-
-    fn apply_builtin(&mut self, builtin: Builtin, args: Vec<Expression>) -> EvalResult<Primitive> {
-        use Builtin::*;
-        use Literal::*;
-        use Primitive::Literal as Lit;
-
-        let evaled_args: EvalResult<Vec<Primitive>> =
-            args.into_iter().map(|arg| self.expression(arg)).collect();
-        let evaled_args = evaled_args?;
-
-        Ok(match (builtin, evaled_args.as_slice()) {
-            /* builtin functions */
-            (IOPrint, &[ref anything]) => {
-                print!("{}", anything.to_repl(self.type_context));
-                Primitive::Tuple(vec![])
-            }
-            (IOPrintLn, &[ref anything]) => {
-                println!("{}", anything.to_repl(self.type_context));
-                Primitive::Tuple(vec![])
-            }
-            (IOGetLine, &[]) => {
-                let mut buf = String::new();
-                std::io::stdin().read_line(&mut buf).expect("Error readling line in 'getline'");
-                StringLit(Rc::new(buf.trim().to_string())).into()
-            }
-            /* Binops */
-            (binop, &[ref lhs, ref rhs]) => match (binop, lhs, rhs) {
-                // TODO need a better way of handling these literals
-                (Add, Lit(Nat(l)), Lit(Nat(r))) => Nat(l + r).into(),
-                (Add, Lit(Int(l)), Lit(Int(r))) => Int(l + r).into(),
-                (Add, Lit(Nat(l)), Lit(Int(r))) => Int((*l as i64) + (*r as i64)).into(),
-                (Add, Lit(Int(l)), Lit(Nat(r))) => Int((*l as i64) + (*r as i64)).into(),
-                (Concatenate, Lit(StringLit(ref s1)), Lit(StringLit(ref s2))) =>
-                    StringLit(Rc::new(format!("{}{}", s1, s2))).into(),
-                (Subtract, Lit(Nat(l)), Lit(Nat(r))) => Nat(l - r).into(),
-                (Multiply, Lit(Nat(l)), Lit(Nat(r))) => Nat(l * r).into(),
-                (Divide, Lit(Nat(l)), Lit(Nat(r))) => Float((*l as f64) / (*r as f64)).into(),
-                (Quotient, Lit(Nat(l)), Lit(Nat(r))) =>
-                    if *r == 0 {
-                        return Err("Divide-by-zero error".into());
-                    } else {
-                        Nat(l / r).into()
-                    },
-                (Modulo, Lit(Nat(l)), Lit(Nat(r))) => Nat(l % r).into(),
-                (Exponentiation, Lit(Nat(l)), Lit(Nat(r))) => Nat(l ^ r).into(),
-                (BitwiseAnd, Lit(Nat(l)), Lit(Nat(r))) => Nat(l & r).into(),
-                (BitwiseOr, Lit(Nat(l)), Lit(Nat(r))) => Nat(l | r).into(),
-
-                /* comparisons */
-                (Equality, Lit(Nat(l)), Lit(Nat(r))) => Bool(l == r).into(),
-                (Equality, Lit(Int(l)), Lit(Int(r))) => Bool(l == r).into(),
-                (Equality, Lit(Float(l)), Lit(Float(r))) => Bool(l == r).into(),
-                (Equality, Lit(Bool(l)), Lit(Bool(r))) => Bool(l == r).into(),
-                (Equality, Lit(StringLit(ref l)), Lit(StringLit(ref r))) => Bool(l == r).into(),
-
-                (NotEqual, Lit(Nat(l)), Lit(Nat(r))) => Bool(l != r).into(),
-                (NotEqual, Lit(Int(l)), Lit(Int(r))) => Bool(l != r).into(),
-                (NotEqual, Lit(Float(l)), Lit(Float(r))) => Bool(l != r).into(),
-                (NotEqual, Lit(Bool(l)), Lit(Bool(r))) => Bool(l != r).into(),
-                (NotEqual, Lit(StringLit(ref l)), Lit(StringLit(ref r))) => Bool(l != r).into(),
-
-                (LessThan, Lit(Nat(l)), Lit(Nat(r))) => Bool(l < r).into(),
-                (LessThan, Lit(Int(l)), Lit(Int(r))) => Bool(l < r).into(),
-                (LessThan, Lit(Float(l)), Lit(Float(r))) => Bool(l < r).into(),
-
-                (LessThanOrEqual, Lit(Nat(l)), Lit(Nat(r))) => Bool(l <= r).into(),
-                (LessThanOrEqual, Lit(Int(l)), Lit(Int(r))) => Bool(l <= r).into(),
-                (LessThanOrEqual, Lit(Float(l)), Lit(Float(r))) => Bool(l <= r).into(),
-
-                (GreaterThan, Lit(Nat(l)), Lit(Nat(r))) => Bool(l > r).into(),
-                (GreaterThan, Lit(Int(l)), Lit(Int(r))) => Bool(l > r).into(),
-                (GreaterThan, Lit(Float(l)), Lit(Float(r))) => Bool(l > r).into(),
-
-                (GreaterThanOrEqual, Lit(Nat(l)), Lit(Nat(r))) => Bool(l >= r).into(),
-                (GreaterThanOrEqual, Lit(Int(l)), Lit(Int(r))) => Bool(l >= r).into(),
-                (GreaterThanOrEqual, Lit(Float(l)), Lit(Float(r))) => Bool(l >= r).into(),
-
-                (binop, lhs, rhs) =>
-                    return Err(format!("Invalid binop expression {:?} {:?} {:?}", lhs, binop, rhs).into()),
-            },
-            (prefix, &[ref arg]) => match (prefix, arg) {
-                (BooleanNot, Lit(Bool(true))) => Bool(false),
-                (BooleanNot, Lit(Bool(false))) => Bool(true),
-                (Negate, Lit(Nat(n))) => Int(-(*n as i64)),
-                (Negate, Lit(Int(n))) => Int(-(*n as i64)),
-                (Negate, Lit(Float(f))) => Float(-(*f as f64)),
-                (Increment, Lit(Int(n))) => Int(*n),
-                (Increment, Lit(Nat(n))) => Nat(*n),
-                _ => return Err("No valid prefix op".into()),
-            }
-            .into(),
-            (x, args) => return Err(format!("bad or unimplemented builtin {:?} | {:?}", x, args).into()),
-        })
-    }
-
-    fn apply_function(
-        &mut self,
-        body: Vec<Statement>,
-        args: Vec<Expression>,
-        self_expr: Option<Expression>,
-    ) -> EvalResult<Primitive> {
-        let self_expr = if let Some(expr) = self_expr { Some(self.expression(expr)?) } else { None };
-        let mut evaluated_args: Vec<Primitive> = vec![];
-        for arg in args.into_iter() {
-            evaluated_args.push(self.expression(arg)?);
-        }
-
-        let mut frame_state = State { memory: self.state.memory.new_scope(None) };
-        let mut evaluator = Evaluator::new(&mut frame_state, self.type_context);
-
-        if let Some(evaled) = self_expr {
-            let mem = Memory::self_param();
-            evaluator.state.memory.insert(mem, MemoryValue::Primitive(evaled));
-        }
-        for (n, evaled) in evaluated_args.into_iter().enumerate() {
-            let n = n as u8;
-            let mem = n.into();
-            evaluator.state.memory.insert(mem, MemoryValue::Primitive(evaled));
-        }
-        evaluator.block(body)
-    }
-}
--- a/schala-lang/src/tree_walk_eval/mod.rs
+++ b/schala-lang/src/tree_walk_eval/mod.rs
@ -1,173 +0,0 @@
-use std::{convert::From, fmt::Write};
-
-use crate::{
-    reduced_ir::{Callable, Expression, FunctionDefinition, Literal, ReducedIR},
-    symbol_table::DefId,
-    type_inference::{TypeContext, TypeId},
-    util::{delim_wrapped, ScopeStack},
-};
-
-mod evaluator;
-mod test;
-
-type EvalResult<T> = Result<T, RuntimeError>;
-
-#[derive(Debug)]
-pub struct State<'a> {
-    memory: ScopeStack<'a, Memory, MemoryValue>,
-}
-
-//TODO - eh, I dunno, maybe it doesn't matter exactly how memory works in the tree-walking
-//evaluator
-#[derive(Debug, PartialEq, Eq, Hash, Clone)]
-enum Memory {
-    Index(u32),
-}
-
-impl Memory {
-    fn self_param() -> Self {
-        Memory::Index(3_999_999)
-    }
-}
-
-// This is for function param lookups, and is a hack
-impl From<u8> for Memory {
-    fn from(n: u8) -> Self {
-        Memory::Index(4_000_000 + (n as u32))
-    }
-}
-
-impl From<&DefId> for Memory {
-    fn from(id: &DefId) -> Self {
-        Self::Index(id.as_u32())
-    }
-}
-
-#[derive(Debug)]
-struct RuntimeError {
-    msg: String,
-}
-
-impl From<String> for RuntimeError {
-    fn from(msg: String) -> Self {
-        Self { msg }
-    }
-}
-
-impl From<&str> for RuntimeError {
-    fn from(msg: &str) -> Self {
-        Self { msg: msg.to_string() }
-    }
-}
-
-impl RuntimeError {
-    #[allow(dead_code)]
-    fn get_msg(&self) -> String {
-        format!("Runtime error: {}", self.msg)
-    }
-}
-
-/// Anything that can be stored in memory; that is, a function definition, or a fully-evaluated
-/// program value.
-#[derive(Debug)]
-enum MemoryValue {
-    Function(FunctionDefinition),
-    Primitive(Primitive),
-}
-
-impl From<Primitive> for MemoryValue {
-    fn from(prim: Primitive) -> Self {
-        Self::Primitive(prim)
-    }
-}
-
-#[derive(Debug)]
-enum RuntimeValue {
-    Expression(Expression),
-    Evaluated(Primitive),
-}
-
-impl From<Expression> for RuntimeValue {
-    fn from(expr: Expression) -> Self {
-        Self::Expression(expr)
-    }
-}
-
-impl From<Primitive> for RuntimeValue {
-    fn from(prim: Primitive) -> Self {
-        Self::Evaluated(prim)
-    }
-}
-
-/// A fully-reduced value
-#[derive(Debug, Clone)]
-enum Primitive {
-    Tuple(Vec<Primitive>),
-    List(Vec<Primitive>),
-    Literal(Literal),
-    Callable(Callable),
-    Object { type_id: TypeId, tag: u32, ordered_fields: Option<Vec<String>>, items: Vec<Primitive> },
-}
-
-impl Primitive {
-    fn to_repl(&self, type_context: &TypeContext) -> String {
-        match self {
-            Primitive::Object { type_id, items, tag, ordered_fields: _ } if items.is_empty() =>
-                type_context.variant_local_name(type_id, *tag).unwrap().to_string(),
-            Primitive::Object { type_id, items, tag, ordered_fields: None } => {
-                format!(
-                    "{}{}",
-                    type_context.variant_local_name(type_id, *tag).unwrap(),
-                    delim_wrapped('(', ')', items.iter().map(|item| item.to_repl(type_context)))
-                )
-            }
-            Primitive::Object { type_id, items, tag, ordered_fields: Some(fields) } => {
-                let mut buf = format!("{} {{ ", type_context.variant_local_name(type_id, *tag).unwrap());
-                for item in fields.iter().zip(items.iter()).map(Some).intersperse(None) {
-                    match item {
-                        Some((name, val)) => write!(buf, "{}: {}", name, val.to_repl(type_context)).unwrap(),
-                        None => write!(buf, ", ").unwrap(),
-                    }
-                }
-                write!(buf, " }}").unwrap();
-                buf
-            }
-            Primitive::Literal(lit) => match lit {
-                Literal::Nat(n) => format!("{}", n),
-                Literal::Int(i) => format!("{}", i),
-                Literal::Float(f) => format!("{}", f),
-                Literal::Bool(b) => format!("{}", b),
-                Literal::StringLit(s) => format!("\"{}\"", s),
-            },
-            Primitive::Tuple(terms) => delim_wrapped('(', ')', terms.iter().map(|x| x.to_repl(type_context))),
-            Primitive::List(terms) => delim_wrapped('[', ']', terms.iter().map(|x| x.to_repl(type_context))),
-            Primitive::Callable(..) => "<some-callable>".to_string(),
-        }
-    }
-
-    fn unit() -> Self {
-        Primitive::Tuple(vec![])
-    }
-}
-
-impl From<Literal> for Primitive {
-    fn from(lit: Literal) -> Self {
-        Primitive::Literal(lit)
-    }
-}
-
-impl<'a> State<'a> {
-    pub fn new() -> Self {
-        Self { memory: ScopeStack::new(Some("global".to_string())) }
-    }
-
-    pub fn evaluate(
-        &mut self,
-        reduced: ReducedIR,
-        type_context: &TypeContext,
-        repl: bool,
-    ) -> Vec<Result<String, String>> {
-        let mut evaluator = evaluator::Evaluator::new(self, type_context);
-        evaluator.evaluate(reduced, repl)
-    }
-}
--- a/schala-lang/src/tree_walk_eval/test.rs
+++ b/schala-lang/src/tree_walk_eval/test.rs
@ -1,564 +0,0 @@
-#![cfg(test)]
-use pretty_assertions::assert_eq;
-use test_case::test_case;
-
-use crate::{
-    symbol_table::SymbolTable,
-    tree_walk_eval::{evaluator::Evaluator, State},
-    type_inference::TypeContext,
-};
-
-fn evaluate_input(input: &str) -> Result<String, String> {
-    let ast = crate::util::quick_ast(input);
-    let mut symbol_table = SymbolTable::new();
-    let mut type_context = TypeContext::new();
-
-    symbol_table.process_ast(&ast, &mut type_context).unwrap();
-
-    let reduced_ir = crate::reduced_ir::reduce(&ast, &symbol_table, &type_context);
-    reduced_ir.debug(&symbol_table);
-    println!("========");
-    symbol_table.debug();
-
-    let mut state = State::new();
-    let mut evaluator = Evaluator::new(&mut state, &type_context);
-    let mut outputs = evaluator.evaluate(reduced_ir, true);
-    outputs.pop().unwrap()
-}
-
-fn eval_assert(input: &str, expected: &str) {
-    assert_eq!(evaluate_input(input), Ok(expected.to_string()));
-}
-
-fn eval_assert_failure(input: &str, expected: &str) {
-    assert_eq!(evaluate_input(input), Err(expected.to_string()));
-}
-
-#[test]
-fn test_basic_eval() {
-    eval_assert("1 + 2", "3");
-    eval_assert("let mut a = 1; a = 2", "()");
-    eval_assert("let mut a = 1; a = a + 2; a", "3");
-}
-
-#[test]
-fn op_eval() {
-    eval_assert("-13", "-13");
-    eval_assert("10 - 2", "8");
-}
-
-#[test]
-fn function_eval() {
-    eval_assert("fn oi(x) { x + 1 }; oi(4)", "5");
-    eval_assert("fn oi(x) { x + 1 }; oi(1+2)", "4");
-}
-
-#[test]
-fn scopes() {
-    let scope_ok = r#"
-    let a = 20
-    fn haha() {
-      let something = 38
-      let a = 10
-      a
-    }
-    haha()
-    "#;
-
-    eval_assert(scope_ok, "10");
-
-    let scope_ok = r#"
-    let a = 20
-    fn queque() {
-      let a = 10
-      a
-    }
-    a
-    "#;
-    eval_assert(scope_ok, "20");
-}
-
-#[test]
-fn eval_scopes_2() {
-    eval_assert(
-        r#"
-fn trad() {
-    let a = 10
-    fn jinner() {
-        let b = 20
-        b
-    }
-
-    a + jinner()
-}
-trad()"#,
-        "30",
-    );
-
-    let err = "No symbol found for name: `a`";
-
-    eval_assert_failure(
-        r#"
-fn trad() {
-    let a = 10
-    fn inner() {
-        let b = 20
-        a + b
-    }
-
-    inner()
-}
-
-trad()
-"#,
-        err,
-    );
-}
-
-#[test]
-fn adt_output_1() {
-    let source = r#"
-
-type Option<T> = Some(T) | None
-let a = Option::None
-let b = Option::Some(10)
-(b, a)
-"#;
-    eval_assert(source, "(Some(10), None)");
-}
-
-#[test]
-fn adt_output_2() {
-    let source = r#"
-type Gobble = Unknown | Rufus { a: Int, torrid: Nat }
-let b = Gobble::Rufus { a: 3, torrid: 99 }
-b
-    "#;
-    eval_assert(source, "Rufus { a: 3, torrid: 99 }");
-
-    let source = r#"
-type Gobble = Unknown | Rufus { a: Int, torrid: Nat }
-let b = Gobble::Rufus { torrid: 3, a: 84 }
-b
-    "#;
-    eval_assert(source, "Rufus { a: 84, torrid: 3 }");
-
-    let source = r#"
-type Gobble = Unknown | Rufus { a: Int, torrid: Nat }
-let b = Gobble::Rufus { a: 84 }
-b
-    "#;
-    eval_assert_failure(source, "Field torrid not specified for record Gobble::Rufus");
-}
-
-#[test]
-fn basic_if_statement() {
-    let source = r#"
-    let a = 10
-    let b = 10
-    if a == b then { 69 } else { 420 }
-    "#;
-    eval_assert(source, "69");
-}
-
-#[test]
-fn basic_patterns_1() {
-    let source = r#"
-let x = 10
-let a = if x is 10 then { 255 } else { 256 }
-let b = if 23 is 99 then { 255 } else { 256 }
-let c = if true is false then { 9 } else { 10 }
-let d = if "xxx" is "yyy" then { 20 } else { 30 }
-(a, b, c, d)
-    "#;
-    eval_assert(source, "(255, 256, 10, 30)");
-}
-
-#[test_case("sanchez", "1")]
-#[test_case("mouri", "2")]
-#[test_case("hella", "3")]
-#[test_case("cyrus", "4")]
-fn basic_patterns_2(input: &str, expected: &str) {
-    let mut source = format!(r#"let x = "{}""#, input);
-    source.push_str(
-        r#"
-if x {
-    is "sanchez" then 1
-    is "mouri" then 2
-    is "hella" then 3
-    is _ then 4
-}
-"#,
-    );
-    eval_assert(&source, expected);
-}
-
-#[test_case(r#"(45, "panda", false, 2.2)"#, r#""yes""#)]
-#[test_case(r#"(99, "panda", false, -2.45)"#, r#""maybe""#)]
-fn tuple_patterns(input: &str, expected: &str) {
-    let mut source = format!("let x = {}", input);
-    source.push_str(
-        r#"
-if x {
-    is (45, "pablo", _, 28.4) then "no"
-    is (_, "panda", _, 2.2) then "yes"
-    is _ then "maybe"
-}"#,
-    );
-
-    eval_assert(&source, expected);
-}
-
-#[test]
-fn record_patterns_1() {
-    let source = r#"
-type Ara = Kueh { a: Int, b: String } | Morbuk
-
-let alpha = Ara::Kueh { a: 10, b: "sanchez" }
-if alpha {
-    is Ara::Kueh { a, b } then (b, a)
-    is _ then ("nooo", 8888)
-}"#;
-    eval_assert(source, r#"("sanchez", 10)"#);
-}
-
-#[test]
-fn record_patterns_2() {
-    let source = r#"
-type Ara = Kueh { a: Int, b: String } | Morbuk
-
-let alpha = Ara::Kueh { a: 10, b: "sanchez" }
-if alpha {
-    is Ara::Kueh { a, b: le_value } then (le_value, (a*2))
-    is _ then ("nooo", 8888)
-}"#;
-    eval_assert(source, r#"("sanchez", 20)"#);
-}
-
-#[test]
-fn record_patterns_3() {
-    let source = r#"
-type Vstsavlobs = { tkveni: Int, b: Ia }
-type Ia = { sitqva: Int, ghmerts: String }
-let b = Vstsavlobs { tkveni: 3, b: Ia::Ia { sitqva: 5, ghmerts: "ooo" } }
-if b {
-    is Vstsavlobs::Vstsavlobs { tkveni: _, b: Ia::Ia { sitqva, ghmerts } } then sitqva
-    is _ then 5000
-}"#;
-    eval_assert(source, "5");
-}
-
-#[test]
-fn if_is_patterns() {
-    let source = r#"
-type Option<T> = Some(T) | None
-let q = "a string"
-let x = Option::Some(9); if x is Option::Some(q) then { q } else { 0 }"#;
-
-    eval_assert(source, "9");
-
-    let source = r#"
-type Option<T> = Some(T) | None
-let q = "a string"
-let outer = 2
-let x = Option::None; if x is Option::Some(q) then { q } else { -2 + outer }"#;
-    eval_assert(source, "0");
-}
-
-#[test]
-fn full_if_matching() {
-    let source = r#"
-type Option<T> = Some(T) | None
-let a = Option::None
-if a { is Option::None then 4; is Option::Some(x) then x }
-    "#;
-    eval_assert(source, "4");
-
-    let source = r#"
-type Option<T> = Some(T) | None
-let sara = Option::Some(99)
-if sara { is Option::None then 1 + 3; is Option::Some(x) then x }
-    "#;
-    eval_assert(source, "99");
-
-    let source = r#"
-let a = 10
-if a { is 10 then "x"; is 4 then "y" }
-    "#;
-    eval_assert(source, "\"x\"");
-
-    let source = r#"
-let a = 10
-if a { is 15 then "x"; is 10 then "y" }
-    "#;
-    eval_assert(source, "\"y\"");
-}
-
-//TODO - I can probably cut down some of these
-#[test]
-fn string_pattern() {
-    let source = r#"
-let a = "foo"
-if a { is "foo" then "x"; is _ then "y" }
-    "#;
-    eval_assert(source, "\"x\"");
-}
-
-#[test]
-fn boolean_pattern() {
-    let source = r#"
-let a = true
-if a {
-  is true then "x"
-  is false then "y"
-}
-"#;
-    eval_assert(source, "\"x\"");
-}
-
-#[test]
-fn boolean_pattern_2() {
-    let source = r#"
-let a = false
-if a { is true then "x"; is false then "y" }
-"#;
-    eval_assert(source, "\"y\"");
-}
-
-#[test]
-fn ignore_pattern() {
-    let source = r#"
-type Option<T> = Some(T) | None
-if Option::Some(10) {
-  is _ then "hella"
-}
-"#;
-    eval_assert(source, "\"hella\"");
-}
-
-#[test]
-fn tuple_pattern() {
-    let source = r#"
-if (1, 2) {
-  is (1, x) then x;
-  is _ then 99
-}
-"#;
-    eval_assert(source, "2");
-}
-
-#[test]
-fn tuple_pattern_2() {
-    let source = r#"
-if (1, 2) {
-  is (10, x) then x
-  is (y, x) then x + y
-}
-"#;
-    eval_assert(source, "3");
-}
-
-#[test]
-fn tuple_pattern_3() {
-    let source = r#"
-if (1, 5) {
-  is (10, x) then x
-  is (1, x) then x
-}
-"#;
-    eval_assert(source, "5");
-}
-
-#[test]
-fn tuple_pattern_4() {
-    let source = r#"
-if (1, 5) {
-  is (10, x) then x
-  is (1, x) then x
-}
-"#;
-    eval_assert(source, "5");
-}
-
-#[test]
-fn prim_obj_pattern() {
-    let source = r#"
-type Stuff = Mulch(Nat) | Jugs(Nat, String) | Mardok
-let a = Stuff::Mulch(20)
-let b = Stuff::Jugs(1, "haha")
-let c = Stuff::Mardok
-
-let x = if a {
-  is Stuff::Mulch(20) then "x"
-  is _ then "ERR"
-}
-
-let y = if b {
-  is Stuff::Mulch(n) then "ERR"
-  is Stuff::Jugs(2, _) then "ERR"
-  is Stuff::Jugs(1, s) then s
-  is _ then "ERR"
-}
-
-let z = if c {
-  is Stuff::Jugs(_, _) then "ERR"
-  is Stuff::Mardok then "NIGH"
-  is _ then "ERR"
-}
-
-(x, y, z)
-"#;
-    eval_assert(source, r#"("x", "haha", "NIGH")"#);
-}
-
-#[test]
-fn basic_lambda_evaluation_1() {
-    let source = r#"
-let q = \(x, y) { x * y }
-let x = q(5, 2)
-let y = \(m, n, o) { m + n + o }(1,2,3)
-(x, y)
-"#;
-
-    eval_assert(source, r"(10, 6)");
-}
-
-#[test]
-fn basic_lambda_evaluation_2() {
-    let source = r#"
-fn milta() {
-  \(x) { x + 33 }
-}
-milta()(10)
-  "#;
-
-    eval_assert(source, "43");
-}
-
-#[test]
-fn import_all() {
-    let source = r#"
-type Option<T> = Some(T) | None
-import Option::*
-let x = Some(9); if x is Some(q) then { q } else { 0 }"#;
-    eval_assert(source, "9");
-}
-
-#[test]
-fn accessors() {
-    let source = r#"
-type Klewos = { a: Int, b: String }
-let value = Klewos::Klewos { a: 50, b: "nah" }
-(value.a, value.b)
-    "#;
-
-    eval_assert(source, r#"(50, "nah")"#);
-}
-
-#[test]
-fn early_return() {
-    let source = r#"
-fn chnurmek(a: Int): Int {
-    if a == 5 then {
-        return 9999;
-    }
-    return (a + 2);
-}
-
-(chnurmek(5), chnurmek(0))
-    "#;
-    eval_assert(source, r#"(9999, 2)"#);
-
-    let source = r#"
-fn marbuk(a: Int, b: Int): (Int, Int) {
-   if a == 5 then {
-        if b == 6 then {
-            return (50, 50);
-        }
-
-        return (a, b + 1)
-   }
-   (a * 100, b * 100)
-}
-
-let x = marbuk(1, 1)
-let y = marbuk(5, 1)
-let z = marbuk(5, 6)
-
-(x, y, z)
-    "#;
-    eval_assert(source, "((100, 100), (5, 2), (50, 50))");
-}
-
-#[test]
-fn loops() {
-    let source = r#"
-let mut a = 0
-let mut count = 0
-while a != 5 {
-    a = a + 1
-    count = count + 100
-}
-
-count
-    "#;
-    eval_assert(source, "500");
-}
-
-#[test]
-fn loops_2() {
-    let source = r#"
-let mut a = 0
-let mut acc = 0
-while a < 10 {
-    acc = acc + 1
-    a = a + 1
-
-    // Without this continue, the output would be 20
-    if a == 5 then {
-        continue
-    }
-
-    acc = acc + 1
-}
-
-acc"#;
-    eval_assert(source, "19");
-}
-
-#[test]
-fn list_literals() {
-    eval_assert(
-        r#"
-let a = [7, 8, 9]
-a
-"#,
-        "[7, 8, 9]",
-    );
-
-    eval_assert(
-        r#"
-let a = [7, 8, 9]
-fn foo() { return 2 }
-(a[0], a[foo()])
-"#,
-        "(7, 9)",
-    );
-}
-
-#[test]
-fn eval_method() {
-    let src = r#"
-type Thing = Thing
-impl Thing {
-    fn a_method() {
-        20
-    }
-
-}
-
-let a = Thing::Thing
-4 + a.a_method()
-    "#;
-    eval_assert(src, "24");
-}
--- a/schala-lang/src/type_inference/mod.rs
+++ b/schala-lang/src/type_inference/mod.rs
@ -1,227 +0,0 @@
-use std::{collections::HashMap, convert::From};
-
-use crate::{
-    ast::{TypeIdentifier, AST},
-    identifier::{define_id_kind, Id, IdStore},
-};
-
-define_id_kind!(TypeItem);
-pub type TypeId = Id<TypeItem>;
-
-pub struct TypeContext {
-    defined_types: HashMap<TypeId, DefinedType>,
-    type_id_store: IdStore<TypeItem>,
-}
-
-impl TypeContext {
-    pub fn new() -> Self {
-        Self { defined_types: HashMap::new(), type_id_store: IdStore::new() }
-    }
-
-    pub fn register_type(&mut self, builder: TypeBuilder) -> TypeId {
-        let type_id = self.type_id_store.fresh();
-
-        let mut pending_variants = vec![];
-        for variant_builder in builder.variants.into_iter() {
-            let members = variant_builder.members;
-            if members.is_empty() {
-                pending_variants.push(Variant { name: variant_builder.name, members: VariantMembers::Unit });
-                continue;
-            }
-            let record_variant = matches!(members.get(0).unwrap(), VariantMemberBuilder::KeyVal(..));
-
-            if record_variant {
-                let pending_members = members.into_iter().map(|var| match var {
-                    VariantMemberBuilder::KeyVal(name, ty) => (name, ty),
-                    _ => panic!("Compiler internal error: variant mismatch"),
-                });
-
-                //TODO make this mapping meaningful
-                let type_ids = pending_members
-                    .into_iter()
-                    .map(|(name, _ty_id)| (name, self.type_id_store.fresh()))
-                    .collect();
-                pending_variants
-                    .push(Variant { name: variant_builder.name, members: VariantMembers::Record(type_ids) });
-            } else {
-                let pending_members = members.into_iter().map(|var| match var {
-                    VariantMemberBuilder::Pending(pending_type) => pending_type,
-                    _ => panic!("Compiler internal error: variant mismatch"),
-                });
-
-                //TODO make this mapping meaningful
-                let type_ids = pending_members.into_iter().map(|_ty_id| self.type_id_store.fresh()).collect();
-
-                pending_variants
-                    .push(Variant { name: variant_builder.name, members: VariantMembers::Tuple(type_ids) });
-            }
-        }
-
-        // Eventually, I will want to have a better way of determining which numeric tag goes with
-        // which variant. For now, just sort them alphabetically.
-        pending_variants.sort_unstable_by(|a, b| a.name.cmp(&b.name));
-
-        let defined = DefinedType { name: builder.name, variants: pending_variants };
-
-        self.defined_types.insert(type_id, defined);
-        type_id
-    }
-
-    pub fn variant_local_name(&self, type_id: &TypeId, tag: u32) -> Option<&str> {
-        self.defined_types
-            .get(type_id)
-            .and_then(|defined| defined.variants.get(tag as usize))
-            .map(|variant| variant.name.as_ref())
-    }
-
-    pub fn lookup_variant_arity(&self, type_id: &TypeId, tag: u32) -> Option<u32> {
-        self.defined_types.get(type_id).and_then(|defined| defined.variants.get(tag as usize)).map(
-            |variant| match &variant.members {
-                VariantMembers::Unit => 0,
-                VariantMembers::Tuple(items) => items.len() as u32,
-                VariantMembers::Record(items) => items.len() as u32,
-            },
-        )
-    }
-
-    pub fn lookup_record_members(&self, type_id: &TypeId, tag: u32) -> Option<&[(String, TypeId)]> {
-        self.defined_types.get(type_id).and_then(|defined| defined.variants.get(tag as usize)).and_then(
-            |variant| match &variant.members {
-                VariantMembers::Record(items) => Some(items.as_ref()),
-                _ => None,
-            },
-        )
-    }
-
-    pub fn lookup_type(&self, type_id: &TypeId) -> Option<&DefinedType> {
-        self.defined_types.get(type_id)
-    }
-
-    //TODO return some kind of overall type later?
-    pub fn typecheck(&mut self, ast: &AST) -> Result<(), TypeError> {
-        Ok(())
-    }
-}
-
-/// A type defined in program source code, as opposed to a builtin.
-#[allow(dead_code)]
-#[derive(Debug)]
-pub struct DefinedType {
-    pub name: String,
-
-    // the variants are in this list according to tag order
-    pub variants: Vec<Variant>,
-}
-
-#[derive(Debug)]
-pub struct Variant {
-    pub name: String,
-    pub members: VariantMembers,
-}
-
-#[derive(Debug)]
-pub enum VariantMembers {
-    Unit,
-    // Should be non-empty
-    Tuple(Vec<TypeId>),
-    Record(Vec<(String, TypeId)>),
-}
-
-/// Represents a type mentioned as a member of another type during the type registration process.
-/// It may not have been registered itself in the relevant context.
-#[allow(dead_code)]
-#[derive(Debug)]
-pub struct PendingType {
-    inner: TypeIdentifier,
-}
-
-impl From<&TypeIdentifier> for PendingType {
-    fn from(type_identifier: &TypeIdentifier) -> Self {
-        Self { inner: type_identifier.clone() }
-    }
-}
-
-#[derive(Debug)]
-pub struct TypeBuilder {
-    name: String,
-    variants: Vec<VariantBuilder>,
-}
-
-impl TypeBuilder {
-    pub fn new(name: &str) -> Self {
-        Self { name: name.to_string(), variants: vec![] }
-    }
-
-    pub fn add_variant(&mut self, vb: VariantBuilder) {
-        self.variants.push(vb);
-    }
-}
-
-#[derive(Debug)]
-pub struct VariantBuilder {
-    name: String,
-    members: Vec<VariantMemberBuilder>,
-}
-
-impl VariantBuilder {
-    pub fn new(name: &str) -> Self {
-        Self { name: name.to_string(), members: vec![] }
-    }
-
-    pub fn add_member(&mut self, member_ty: PendingType) {
-        self.members.push(VariantMemberBuilder::Pending(member_ty));
-    }
-
-    // You can't call this and `add_member` on the same fn, there should be a runtime error when
-    // that's detected.
-    pub fn add_record_member(&mut self, name: &str, ty: PendingType) {
-        self.members.push(VariantMemberBuilder::KeyVal(name.to_string(), ty));
-    }
-}
-
-#[derive(Debug)]
-enum VariantMemberBuilder {
-    Pending(PendingType),
-    KeyVal(String, PendingType),
-}
-
-#[derive(Debug, Clone)]
-pub struct TypeError {
-    pub msg: String,
-}
-
-#[allow(dead_code)]
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub enum TypeConst {
-    Unit,
-    Nat,
-    Int,
-    Float,
-    StringT,
-    Bool,
-    Ordering,
-}
-
-#[allow(dead_code)]
-#[derive(Debug, Clone, PartialEq)]
-pub enum Type {
-    Const(TypeConst),
-    //Var(TypeVar),
-    Arrow { params: Vec<Type>, ret: Box<Type> },
-    Compound { ty_name: String, args: Vec<Type> },
-}
-
-macro_rules! ty {
-    ($type_name:ident) => {
-        Type::Const(crate::type_inference::TypeConst::$type_name)
-    };
-    ($t1:ident -> $t2:ident) => {
-        Type::Arrow { params: vec![ty!($t1)], ret: Box::new(ty!($t2)) }
-    };
-    ($t1:ident -> $t2:ident -> $t3:ident) => {
-        Type::Arrow { params: vec![ty!($t1), ty!($t2)], ret: Box::new(ty!($t3)) }
-    };
-    ($type_list:ident, $ret_type:ident) => {
-        Type::Arrow { params: $type_list, ret: Box::new($ret_type) }
-    };
-}
--- a/schala-lang/src/util.rs
+++ b/schala-lang/src/util.rs
@ -1,85 +0,0 @@
-use std::{cmp::Eq, collections::HashMap, fmt::Write, hash::Hash};
-
-/// Utility function for printing a comma-delimited list of things
-pub(crate) fn delim_wrapped(lhs: char, rhs: char, terms: impl Iterator<Item = String>) -> String {
-    let mut buf = String::new();
-    write!(buf, "{}", lhs).unwrap();
-    for term in terms.map(Some).intersperse(None) {
-        match term {
-            Some(e) => write!(buf, "{}", e).unwrap(),
-            None => write!(buf, ", ").unwrap(),
-        };
-    }
-    write!(buf, "{}", rhs).unwrap();
-    buf
-}
-
-#[derive(Default, Debug)]
-pub struct ScopeStack<'a, T: 'a, V: 'a, N = String>
-where T: Hash + Eq
-{
-    parent: Option<&'a ScopeStack<'a, T, V, N>>,
-    values: HashMap<T, V>,
-    scope_name: Option<N>,
-}
-
-impl<'a, T, V, N> ScopeStack<'a, T, V, N>
-where T: Hash + Eq
-{
-    pub fn new(scope_name: Option<N>) -> Self
-    where T: Hash + Eq {
-        ScopeStack { parent: None, values: HashMap::new(), scope_name }
-    }
-    pub fn insert(&mut self, key: T, value: V)
-    where T: Hash + Eq {
-        self.values.insert(key, value);
-    }
-    pub fn lookup(&self, key: &T) -> Option<&V>
-    where T: Hash + Eq {
-        match (self.values.get(key), self.parent) {
-            (None, None) => None,
-            (None, Some(parent)) => parent.lookup(key),
-            (Some(value), _) => Some(value),
-        }
-    }
-
-    pub fn new_scope(&'a self, scope_name: Option<N>) -> Self
-    where T: Hash + Eq {
-        ScopeStack { parent: Some(self), values: HashMap::default(), scope_name }
-    }
-
-    #[allow(dead_code)]
-    pub fn lookup_with_scope(&self, key: &T) -> Option<(&V, Option<&N>)>
-    where T: Hash + Eq {
-        match (self.values.get(key), self.parent) {
-            (None, None) => None,
-            (None, Some(parent)) => parent.lookup_with_scope(key),
-            (Some(value), _) => Some((value, self.scope_name.as_ref())),
-        }
-    }
-
-    pub fn get_name(&self) -> Option<&N> {
-        self.scope_name.as_ref()
-    }
-}
-
-/// Quickly create an AST from a string, with no error checking. For test use only
-#[cfg(test)]
-pub fn quick_ast(input: &str) -> crate::ast::AST {
-    let mut parser = crate::parsing::Parser::new();
-    let output = parser.parse(input);
-    match output {
-        Ok(output) => output,
-        Err(err) => {
-            println!("Parse error: {}", err.msg);
-            panic!();
-        }
-    }
-}
-
-#[allow(unused_macros)]
-macro_rules! rc {
-    ($string:tt) => {
-        Rc::new(stringify!($string).to_string())
-    };
-}
--- a/schala-repl/Cargo.toml
+++ b/schala-repl/Cargo.toml
@ -2,18 +2,19 @@
 name = "schala-repl"
 version = "0.1.0"
 authors = ["greg <greg.shuflin@protonmail.com>"]
-edition = "2021"
+edition = "2018"

 [dependencies]
 llvm-sys = "70.0.2"
 take_mut = "0.2.2"
-itertools = "0.10"
+itertools = "0.5.8"
+getopts = "0.2.18"
 lazy_static = "0.2.8"
 maplit = "*"
 colored = "1.8"
-serde = "1.0"
-serde_derive = "1.0"
-serde_json = "1.0"
+serde = "1.0.91"
+serde_derive = "1.0.91"
+serde_json = "1.0.15"
 phf = "0.7.12"
 includedir = "0.2.0"
 linefeed = "0.6.0"
--- a/schala-repl/build.rs
+++ b/schala-repl/build.rs
@ -3,5 +3,8 @@ extern crate includedir_codegen;
 use includedir_codegen::Compression;

 fn main() {
-    includedir_codegen::start("WEBFILES").dir("../static", Compression::Gzip).build("static.rs").unwrap();
+    includedir_codegen::start("WEBFILES")
+        .dir("../static", Compression::Gzip)
+        .build("static.rs")
+        .unwrap();
 }
--- a/schala-repl/src/command_tree.rs
+++ b/schala-repl/src/command_tree.rs
@ -1,116 +0,0 @@
-use colored::*;
-
-use crate::{
-    directive_actions::DirectiveAction, language::ProgrammingLanguageInterface, InterpreterDirectiveOutput,
-    Repl,
-};
-
-/// A CommandTree is either a `Terminal` or a `NonTerminal`. When command parsing reaches the first
-/// Terminal, it will use the `DirectiveAction` found there to find an appropriate function to execute,
-/// and then execute it with any remaining arguments
-#[derive(Clone)]
-pub enum CommandTree {
-    Terminal {
-        name: String,
-        children: Vec<CommandTree>,
-        help_msg: Option<String>,
-        action: DirectiveAction,
-    },
-    NonTerminal {
-        name: String,
-        children: Vec<CommandTree>,
-        help_msg: Option<String>,
-        action: DirectiveAction,
-    },
-    Top(Vec<CommandTree>),
-}
-
-impl CommandTree {
-    pub fn nonterm_no_further_tab_completions(s: &str, help: Option<&str>) -> CommandTree {
-        CommandTree::NonTerminal {
-            name: s.to_string(),
-            help_msg: help.map(|x| x.to_string()),
-            children: vec![],
-            action: DirectiveAction::Null,
-        }
-    }
-
-    pub fn terminal(
-        s: &str,
-        help: Option<&str>,
-        children: Vec<CommandTree>,
-        action: DirectiveAction,
-    ) -> CommandTree {
-        CommandTree::Terminal { name: s.to_string(), help_msg: help.map(|x| x.to_string()), children, action }
-    }
-
-    pub fn nonterm(s: &str, help: Option<&str>, children: Vec<CommandTree>) -> CommandTree {
-        CommandTree::NonTerminal {
-            name: s.to_string(),
-            help_msg: help.map(|x| x.to_string()),
-            children,
-            action: DirectiveAction::Null,
-        }
-    }
-
-    pub fn get_cmd(&self) -> &str {
-        match self {
-            CommandTree::Terminal { name, .. } => name.as_str(),
-            CommandTree::NonTerminal { name, .. } => name.as_str(),
-            CommandTree::Top(_) => "",
-        }
-    }
-    pub fn get_help(&self) -> &str {
-        match self {
-            CommandTree::Terminal { help_msg, .. } =>
-                help_msg.as_ref().map(|s| s.as_str()).unwrap_or("<no help text provided>"),
-            CommandTree::NonTerminal { help_msg, .. } =>
-                help_msg.as_ref().map(|s| s.as_str()).unwrap_or("<no help text provided>"),
-            CommandTree::Top(_) => "",
-        }
-    }
-    pub fn get_children(&self) -> &Vec<CommandTree> {
-        use CommandTree::*;
-        match self {
-            Terminal { children, .. } | NonTerminal { children, .. } | Top(children) => children,
-        }
-    }
-    pub fn get_subcommands(&self) -> Vec<&str> {
-        self.get_children().iter().map(|x| x.get_cmd()).collect()
-    }
-
-    pub fn perform<L: ProgrammingLanguageInterface>(
-        &self,
-        repl: &mut Repl<L>,
-        arguments: &[&str],
-    ) -> InterpreterDirectiveOutput {
-        let mut dir_pointer: &CommandTree = self;
-        let mut idx = 0;
-
-        let res: Result<(DirectiveAction, usize), String> = loop {
-            match dir_pointer {
-                CommandTree::Top(subcommands) | CommandTree::NonTerminal { children: subcommands, .. } => {
-                    let next_command = match arguments.get(idx) {
-                        Some(cmd) => cmd,
-                        None => break Err("Command requires arguments".to_owned()),
-                    };
-                    idx += 1;
-                    match subcommands.iter().find(|sc| sc.get_cmd() == *next_command) {
-                        Some(command_tree) => {
-                            dir_pointer = command_tree;
-                        }
-                        None => break Err(format!("Command {} not found", next_command)),
-                    };
-                }
-                CommandTree::Terminal { action, .. } => {
-                    break Ok((action.clone(), idx));
-                }
-            }
-        };
-
-        match res {
-            Ok((action, idx)) => action.perform(repl, &arguments[idx..]),
-            Err(err) => Some(err.red().to_string()),
-        }
-    }
-}
--- a/schala-repl/src/directive_actions.rs
+++ b/schala-repl/src/directive_actions.rs
@ -1,77 +0,0 @@
-use std::fmt::Write as FmtWrite;
-
-use crate::{
-    help::help,
-    language::{LangMetaRequest, LangMetaResponse, ProgrammingLanguageInterface},
-    InterpreterDirectiveOutput, Repl,
-};
-
-#[derive(Debug, Clone)]
-pub enum DirectiveAction {
-    Null,
-    Help,
-    QuitProgram,
-    ListPasses,
-    TotalTime(bool),
-    StageTime(bool),
-    Doc,
-}
-
-impl DirectiveAction {
-    pub fn perform<L: ProgrammingLanguageInterface>(
-        &self,
-        repl: &mut Repl<L>,
-        arguments: &[&str],
-    ) -> InterpreterDirectiveOutput {
-        use DirectiveAction::*;
-        match self {
-            Null => None,
-            Help => help(repl, arguments),
-            QuitProgram => {
-                repl.save_before_exit();
-                ::std::process::exit(0)
-            }
-            ListPasses => {
-                let pass_names = match repl.language_state.request_meta(LangMetaRequest::StageNames) {
-                    LangMetaResponse::StageNames(names) => names,
-                    _ => vec![],
-                };
-
-                let mut buf = String::new();
-                for pass in pass_names.iter().map(Some).intersperse(None) {
-                    match pass {
-                        Some(pass) => write!(buf, "{}", pass).unwrap(),
-                        None => write!(buf, " -> ").unwrap(),
-                    }
-                }
-                Some(buf)
-            }
-            TotalTime(value) => {
-                repl.options.show_total_time = *value;
-                None
-            }
-            StageTime(value) => {
-                repl.options.show_stage_times = *value;
-                None
-            }
-            Doc => doc(repl, arguments),
-        }
-    }
-}
-
-fn doc<L: ProgrammingLanguageInterface>(
-    repl: &mut Repl<L>,
-    arguments: &[&str],
-) -> InterpreterDirectiveOutput {
-    arguments
-        .get(0)
-        .map(|cmd| {
-            let source = cmd.to_string();
-            let meta = LangMetaRequest::Docs { source };
-            match repl.language_state.request_meta(meta) {
-                LangMetaResponse::Docs { doc_string } => Some(doc_string),
-                _ => Some("Invalid doc response".to_owned()),
-            }
-        })
-        .unwrap_or_else(|| Some(":docs needs an argument".to_owned()))
-}
--- a/schala-repl/src/directives.rs
+++ b/schala-repl/src/directives.rs
@ -1,68 +0,0 @@
-use crate::{command_tree::CommandTree, directive_actions::DirectiveAction};
-
-pub fn directives_from_pass_names(pass_names: &[String]) -> CommandTree {
-    let passes_directives: Vec<CommandTree> = pass_names
-        .iter()
-        .map(|pass_name| {
-            if pass_name == "parsing" {
-                CommandTree::nonterm(
-                    pass_name,
-                    None,
-                    vec![
-                        CommandTree::nonterm_no_further_tab_completions("compact", None),
-                        CommandTree::nonterm_no_further_tab_completions("expanded", None),
-                        CommandTree::nonterm_no_further_tab_completions("trace", None),
-                    ],
-                )
-            } else {
-                CommandTree::nonterm_no_further_tab_completions(pass_name, None)
-            }
-        })
-        .collect();
-    CommandTree::Top(get_list(&passes_directives, true))
-}
-
-fn get_list(passes_directives: &[CommandTree], include_help: bool) -> Vec<CommandTree> {
-    use DirectiveAction::*;
-
-    vec![
-        CommandTree::terminal("exit", Some("exit the REPL"), vec![], QuitProgram),
-        //TODO there should be an alias for this
-        CommandTree::terminal("quit", Some("exit the REPL"), vec![], QuitProgram),
-        CommandTree::terminal(
-            "help",
-            Some("Print this help message"),
-            if include_help { get_list(passes_directives, false) } else { vec![] },
-            Help,
-        ),
-        CommandTree::nonterm(
-            "debug",
-            Some("Configure debug information"),
-            vec![
-                CommandTree::terminal(
-                    "list-passes",
-                    Some("List all registered compiler passes"),
-                    vec![],
-                    ListPasses,
-                ),
-                CommandTree::nonterm(
-                    "total-time",
-                    None,
-                    vec![
-                        CommandTree::terminal("on", None, vec![], TotalTime(true)),
-                        CommandTree::terminal("off", None, vec![], TotalTime(false)),
-                    ],
-                ),
-                CommandTree::nonterm(
-                    "stage-times",
-                    Some("Computation time per-stage"),
-                    vec![
-                        CommandTree::terminal("on", None, vec![], StageTime(true)),
-                        CommandTree::terminal("off", None, vec![], StageTime(false)),
-                    ],
-                ),
-            ],
-        ),
-        CommandTree::terminal("doc", Some("Get language-specific help for an item"), vec![], Doc),
-    ]
-}
--- a/schala-repl/src/help.rs
+++ b/schala-repl/src/help.rs
@ -1,63 +0,0 @@
-use std::fmt::Write as FmtWrite;
-
-use colored::*;
-
-use crate::{
-    command_tree::CommandTree, language::ProgrammingLanguageInterface, InterpreterDirectiveOutput, Repl,
-};
-
-pub fn help<L: ProgrammingLanguageInterface>(
-    repl: &mut Repl<L>,
-    arguments: &[&str],
-) -> InterpreterDirectiveOutput {
-    match arguments {
-        [] => global_help(repl),
-        commands => {
-            let dirs = repl.get_directives();
-            Some(match get_directive_from_commands(commands, &dirs) {
-                None => format!("Directive `{}` not found", commands.last().unwrap()),
-                Some(dir) => {
-                    let mut buf = String::new();
-                    let cmd = dir.get_cmd();
-                    let children = dir.get_children();
-                    writeln!(buf, "`{}` - {}", cmd, dir.get_help()).unwrap();
-                    for sub in children.iter() {
-                        writeln!(buf, "\t`{} {}` - {}", cmd, sub.get_cmd(), sub.get_help()).unwrap();
-                    }
-                    buf
-                }
-            })
-        }
-    }
-}
-
-fn get_directive_from_commands<'a>(commands: &[&str], dirs: &'a CommandTree) -> Option<&'a CommandTree> {
-    let mut directive_list = dirs.get_children();
-    let mut matched_directive = None;
-    for cmd in commands {
-        let found = directive_list.iter().find(|directive| directive.get_cmd() == *cmd);
-        if let Some(dir) = found {
-            directive_list = dir.get_children();
-        }
-
-        matched_directive = found;
-    }
-    matched_directive
-}
-
-fn global_help<L: ProgrammingLanguageInterface>(repl: &mut Repl<L>) -> InterpreterDirectiveOutput {
-    let mut buf = String::new();
-
-    writeln!(buf, "{} version {}", "Schala REPL".bright_red().bold(), crate::VERSION_STRING).unwrap();
-    writeln!(buf, "-----------------------").unwrap();
-
-    for directive in repl.get_directives().get_children() {
-        writeln!(buf, "{}{} - {}", repl.sigil, directive.get_cmd(), directive.get_help()).unwrap();
-    }
-
-    writeln!(buf).unwrap();
-    writeln!(buf, "Language-specific help for {}", <L as ProgrammingLanguageInterface>::language_name())
-        .unwrap();
-    writeln!(buf, "-----------------------").unwrap();
-    Some(buf)
-}
--- a/schala-repl/src/language.rs
+++ b/schala-repl/src/language.rs
@ -1,56 +1,80 @@
-use std::{collections::HashSet, time};
+use std::time;
+use std::collections::HashSet;

 pub trait ProgrammingLanguageInterface {
-    type Config: Default + Clone;
-    fn language_name() -> String;
-    fn source_file_suffix() -> String;
+  fn get_language_name(&self) -> String;
+  fn get_source_file_suffix(&self) -> String;

-    fn run_computation(&mut self, _request: ComputationRequest<Self::Config>) -> ComputationResponse;
-
-    fn request_meta(&mut self, _request: LangMetaRequest) -> LangMetaResponse {
-        LangMetaResponse::Custom { kind: "not-implemented".to_owned(), value: format!("") }
+  fn run_computation(&mut self, _request: ComputationRequest) -> ComputationResponse {
+    ComputationResponse {
+      main_output: Err(format!("Computation pipeline not implemented")),
+      global_output_stats: GlobalOutputStats::default(),
+      debug_responses: vec![],
    }
+  }
+
+  fn request_meta(&mut self, _request: LangMetaRequest) -> LangMetaResponse {
+    LangMetaResponse::Custom { kind: format!("not-implemented"), value: format!("") }
+  }
 }

-pub struct ComputationRequest<'a, T> {
-    pub source: &'a str,
-    pub config: T,
-    pub debug_requests: HashSet<DebugAsk>,
+pub struct ComputationRequest<'a> {
+  pub source: &'a str,
+  pub debug_requests: HashSet<DebugAsk>,
 }

 pub struct ComputationResponse {
-    pub main_output: Result<String, String>,
-    pub global_output_stats: GlobalOutputStats,
-    pub debug_responses: Vec<DebugResponse>,
+  pub main_output: Result<String, String>,
+  pub global_output_stats: GlobalOutputStats,
+  pub debug_responses: Vec<DebugResponse>,
 }

 #[derive(Default, Debug)]
 pub struct GlobalOutputStats {
-    pub total_duration: time::Duration,
-    pub stage_durations: Vec<(String, time::Duration)>,
+  pub total_duration: time::Duration,
+  pub stage_durations: Vec<(String, time::Duration)>
 }

 #[derive(Debug, Clone, Hash, Eq, PartialEq, Deserialize, Serialize)]
 pub enum DebugAsk {
-    Timing,
-    ByStage { stage_name: String, token: Option<String> },
+  Timing,
+  ByStage { stage_name: String, token: Option<String> },
+}
+
+impl DebugAsk {
+  pub fn is_for_stage(&self, name: &str) -> bool {
+    match self {
+      DebugAsk::ByStage { stage_name, .. } if stage_name == name => true,
+      _ => false
+    }
+  }
 }

 pub struct DebugResponse {
-    pub ask: DebugAsk,
-    pub value: String,
+  pub ask: DebugAsk,
+  pub value: String
 }

 pub enum LangMetaRequest {
-    StageNames,
-    Docs { source: String },
-    Custom { kind: String, value: String },
-    ImmediateDebug(DebugAsk),
+  StageNames,
+  Docs {
+    source: String,
+  },
+  Custom {
+    kind: String,
+    value: String
+  },
+  ImmediateDebug(DebugAsk),
 }

 pub enum LangMetaResponse {
-    StageNames(Vec<String>),
-    Docs { doc_string: String },
-    Custom { kind: String, value: String },
-    ImmediateDebug(DebugResponse),
+  StageNames(Vec<String>),
+  Docs {
+    doc_string: String,
+  },
+  Custom {
+    kind: String,
+    value: String
+  },
+  ImmediateDebug(DebugResponse),
 }
--- a/schala-repl/src/lib.rs
+++ b/schala-repl/src/lib.rs
@ -1,249 +1,92 @@
-#![feature(box_patterns, proc_macro_hygiene, decl_macro, iter_intersperse)]
+#![feature(link_args)]
+#![feature(slice_patterns, box_patterns, box_syntax, proc_macro_hygiene, decl_macro)]
+#![feature(plugin)]
+extern crate getopts;
+extern crate linefeed;
+extern crate itertools;
+extern crate colored;

 #[macro_use]
 extern crate serde_derive;
+extern crate serde_json;
 extern crate includedir;
 extern crate phf;
-extern crate serde_json;

-mod command_tree;
+use std::collections::HashSet;
+use std::path::Path;
+use std::fs::File;
+use std::io::Read;
+use std::process::exit;
+
+mod repl;
 mod language;
-use self::command_tree::CommandTree;
-mod repl_options;
-use repl_options::ReplOptions;
-mod directive_actions;
-mod directives;
-use directives::directives_from_pass_names;
-mod help;
-mod response;
-use std::{collections::HashSet, sync::Arc};

-use colored::*;
-pub use language::{
-    ComputationRequest, ComputationResponse, DebugAsk, DebugResponse, GlobalOutputStats, LangMetaRequest,
-    LangMetaResponse, ProgrammingLanguageInterface,
-};
-use response::ReplResponse;
+pub use language::{ProgrammingLanguageInterface,
+ComputationRequest, ComputationResponse,
+LangMetaRequest, LangMetaResponse,
+DebugResponse, DebugAsk, GlobalOutputStats};

 include!(concat!(env!("OUT_DIR"), "/static.rs"));
-const VERSION_STRING: &str = "0.1.0";
+const VERSION_STRING: &'static str = "0.1.0";

-const HISTORY_SAVE_FILE: &str = ".schala_history";
-const OPTIONS_SAVE_FILE: &str = ".schala_repl";
+pub fn start_repl(langs: Vec<Box<dyn ProgrammingLanguageInterface>>) {
+  let options = command_line_options().parse(std::env::args()).unwrap_or_else(|e| {
+    println!("{:?}", e);
+    exit(1);
+  });

-type InterpreterDirectiveOutput = Option<String>;
+  if options.opt_present("help") {
+    println!("{}", command_line_options().usage("Schala metainterpreter"));
+    exit(0);
+  }

-pub struct Repl<L: ProgrammingLanguageInterface> {
-    /// If this is the first character typed by a user into the repl, the following
-    /// will be interpreted as a directive to the REPL rather than a command in the
-    /// running programming language.
-    sigil: char,
-    line_reader: ::linefeed::interface::Interface<::linefeed::terminal::DefaultTerminal>,
-    language_state: L,
-    options: ReplOptions,
+  match options.free[..] {
+    [] | [_] => {
+      let mut repl = repl::Repl::new(langs);
+      repl.run_repl();
+    }
+    [_, ref filename, ..] => {
+      run_noninteractive(filename, langs);
+    }
+  };
 }

-#[derive(Clone)]
-enum PromptStyle {
-    Normal,
-    Multiline,
+fn run_noninteractive(filename: &str, languages: Vec<Box<dyn ProgrammingLanguageInterface>>) {
+  let path = Path::new(filename);
+  let ext = path.extension().and_then(|e| e.to_str()).unwrap_or_else(|| {
+    println!("Source file lacks extension");
+    exit(1);
+  });
+  let mut language = Box::new(languages.into_iter().find(|lang| lang.get_source_file_suffix() == ext)
+    .unwrap_or_else(|| {
+      println!("Extension .{} not recognized", ext);
+      exit(1);
+    }));
+
+  let mut source_file = File::open(path).unwrap();
+  let mut buffer = String::new();
+  source_file.read_to_string(&mut buffer).unwrap();
+
+  let request = ComputationRequest {
+    source: &buffer,
+    debug_requests: HashSet::new(),
+  };
+
+  let response = language.run_computation(request);
+  match response.main_output {
+    Ok(s) => println!("{}", s),
+    Err(s) => println!("{}", s)
+  };
 }

-impl<L: ProgrammingLanguageInterface> Repl<L> {
-    pub fn new(initial_state: L) -> Self {
-        use linefeed::Interface;
-        let line_reader = Interface::new("schala-repl").unwrap();
-        let sigil = ':';

-        Repl { sigil, line_reader, language_state: initial_state, options: ReplOptions::new() }
-    }
-
-    pub fn run_repl(&mut self, config: L::Config) {
-        println!("Schala meta-interpeter version {}", VERSION_STRING);
-        println!("Type {} for help with the REPL", format!("{}help", self.sigil).bright_green().bold());
-        self.load_options();
-        self.handle_repl_loop(config);
-        self.save_before_exit();
-        println!("Exiting...");
-    }
-
-    fn load_options(&mut self) {
-        self.line_reader.load_history(HISTORY_SAVE_FILE).unwrap_or(());
-        match ReplOptions::load_from_file(OPTIONS_SAVE_FILE) {
-            Ok(options) => {
-                self.options = options;
-            }
-            Err(e) => eprintln!("{}", e),
-        }
-    }
-
-    fn handle_repl_loop(&mut self, config: L::Config) {
-        use linefeed::ReadResult::*;
-
-        'main: loop {
-            macro_rules! match_or_break {
-                ($line:expr) => {
-                    match $line {
-                        Err(e) => {
-                            println!("readline IO Error: {}", e);
-                            break 'main;
-                        }
-                        Ok(Eof) | Ok(Signal(_)) => break 'main,
-                        Ok(Input(ref input)) => input,
-                    }
-                };
-            }
-            self.update_line_reader();
-            let line = self.line_reader.read_line();
-            let input: &str = match_or_break!(line);
-
-            self.line_reader.add_history_unique(input.to_string());
-            let mut chars = input.chars().peekable();
-            let repl_responses = match chars.next() {
-                Some(ch) if ch == self.sigil =>
-                    if chars.peek() == Some(&'{') {
-                        let mut buf = String::new();
-                        buf.push_str(input.get(2..).unwrap());
-                        'multiline: loop {
-                            self.set_prompt(PromptStyle::Multiline);
-                            let new_line = self.line_reader.read_line();
-                            let new_input = match_or_break!(new_line);
-                            if new_input.starts_with(":}") {
-                                break 'multiline;
-                            } else {
-                                buf.push_str(new_input);
-                                buf.push('\n');
-                            }
-                        }
-                        self.handle_input(&buf, &config)
-                    } else {
-                        if let Some(output) = self.handle_interpreter_directive(input.get(1..).unwrap()) {
-                            println!("{}", output);
-                        }
-                        continue;
-                    },
-                _ => self.handle_input(input, &config),
-            };
-
-            for repl_response in repl_responses.iter() {
-                println!("{}", repl_response);
-            }
-        }
-    }
-
-    fn update_line_reader(&mut self) {
-        let tab_complete_handler = TabCompleteHandler::new(self.sigil, self.get_directives());
-        self.line_reader.set_completer(Arc::new(tab_complete_handler)); //TODO fix this here
-        self.set_prompt(PromptStyle::Normal);
-    }
-
-    fn set_prompt(&mut self, prompt_style: PromptStyle) {
-        let prompt_str = match prompt_style {
-            PromptStyle::Normal => ">> ",
-            PromptStyle::Multiline => ">| ",
-        };
-
-        self.line_reader.set_prompt(prompt_str).unwrap();
-    }
-
-    fn save_before_exit(&self) {
-        self.line_reader.save_history(HISTORY_SAVE_FILE).unwrap_or(());
-        self.options.save_to_file(OPTIONS_SAVE_FILE);
-    }
-
-    fn handle_interpreter_directive(&mut self, input: &str) -> InterpreterDirectiveOutput {
-        let arguments: Vec<&str> = input.split_whitespace().collect();
-
-        if arguments.is_empty() {
-            return None;
-        }
-
-        let directives = self.get_directives();
-        directives.perform(self, &arguments)
-    }
-
-    fn handle_input(&mut self, input: &str, config: &L::Config) -> Vec<ReplResponse> {
-        let mut debug_requests = HashSet::new();
-        for ask in self.options.debug_asks.iter() {
-            debug_requests.insert(ask.clone());
-        }
-
-        let request = ComputationRequest { source: input, config: config.clone(), debug_requests };
-        let response = self.language_state.run_computation(request);
-        response::handle_computation_response(response, &self.options)
-    }
-
-    fn get_directives(&mut self) -> CommandTree {
-        let pass_names = match self.language_state.request_meta(LangMetaRequest::StageNames) {
-            LangMetaResponse::StageNames(names) => names,
-            _ => vec![],
-        };
-
-        directives_from_pass_names(&pass_names)
-    }
-}
-
-struct TabCompleteHandler {
-    sigil: char,
-    top_level_commands: CommandTree,
-}
-
-use linefeed::{
-    complete::{Completer, Completion},
-    terminal::Terminal,
-};
-
-impl TabCompleteHandler {
-    fn new(sigil: char, top_level_commands: CommandTree) -> TabCompleteHandler {
-        TabCompleteHandler { top_level_commands, sigil }
-    }
-}
-
-impl<T: Terminal> Completer<T> for TabCompleteHandler {
-    fn complete(
-        &self,
-        word: &str,
-        prompter: &::linefeed::prompter::Prompter<T>,
-        start: usize,
-        _end: usize,
-    ) -> Option<Vec<Completion>> {
-        let line = prompter.buffer();
-
-        if !line.starts_with(self.sigil) {
-            return None;
-        }
-
-        let mut words = line[1..(if start == 0 { 1 } else { start })].split_whitespace();
-        let mut completions = Vec::new();
-        let mut command_tree: Option<&CommandTree> = Some(&self.top_level_commands);
-
-        loop {
-            match words.next() {
-                None => {
-                    let top = matches!(command_tree, Some(CommandTree::Top(_)));
-                    let word = if top { word.get(1..).unwrap() } else { word };
-                    for cmd in command_tree.map(|x| x.get_subcommands()).unwrap_or_default().into_iter() {
-                        if cmd.starts_with(word) {
-                            completions.push(Completion {
-                                completion: format!("{}{}", if top { ":" } else { "" }, cmd),
-                                display: Some(cmd.to_string()),
-                                suffix: ::linefeed::complete::Suffix::Some(' '),
-                            })
-                        }
-                    }
-                    break;
-                }
-                Some(s) => {
-                    let new_ptr: Option<&CommandTree> = command_tree.and_then(|cm| match cm {
-                        CommandTree::Top(children) => children.iter().find(|c| c.get_cmd() == s),
-                        CommandTree::NonTerminal { children, .. } =>
-                            children.iter().find(|c| c.get_cmd() == s),
-                        CommandTree::Terminal { children, .. } => children.iter().find(|c| c.get_cmd() == s),
-                    });
-                    command_tree = new_ptr;
-                }
-            }
-        }
-        Some(completions)
-    }
+fn command_line_options() -> getopts::Options {
+  let mut options = getopts::Options::new();
+  options.optflag("h",
+                  "help",
+                  "Show help text");
+  options.optflag("w",
+                  "webapp",
+                  "Start up web interpreter");
+  options
 }
--- a/schala-repl/src/repl/command_tree.rs
+++ b/schala-repl/src/repl/command_tree.rs
@ -0,0 +1,99 @@
+use super::{Repl, InterpreterDirectiveOutput};
+use crate::repl::directive_actions::DirectiveAction;
+use colored::*;
+
+/// A CommandTree is either a `Terminal` or a `NonTerminal`. When command parsing reaches the first
+/// Terminal, it will use the `DirectiveAction` found there to find an appropriate function to execute,
+/// and then execute it with any remaining arguments
+#[derive(Clone)]
+pub enum CommandTree {
+  Terminal {
+    name: String,
+    children: Vec<CommandTree>,
+    help_msg: Option<String>,
+    action: DirectiveAction,
+  },
+  NonTerminal {
+    name: String,
+    children: Vec<CommandTree>,
+    help_msg: Option<String>,
+    action: DirectiveAction,
+  },
+  Top(Vec<CommandTree>),
+}
+
+impl CommandTree {
+  pub fn nonterm_no_further_tab_completions(s: &str, help: Option<&str>) -> CommandTree {
+    CommandTree::NonTerminal {name: s.to_string(), help_msg: help.map(|x| x.to_string()), children: vec![], action: DirectiveAction::Null }
+  }
+
+  pub fn terminal(s: &str, help: Option<&str>, children: Vec<CommandTree>, action: DirectiveAction) -> CommandTree {
+    CommandTree::Terminal {name: s.to_string(), help_msg: help.map(|x| x.to_string()), children, action}
+  }
+
+  pub fn nonterm(s: &str, help: Option<&str>, children: Vec<CommandTree>) -> CommandTree {
+    CommandTree::NonTerminal {
+      name: s.to_string(),
+      help_msg: help.map(|x| x.to_string()),
+      children,
+      action: DirectiveAction::Null
+    }
+  }
+
+  pub fn get_cmd(&self) -> &str {
+    match self {
+      CommandTree::Terminal { name, .. } => name.as_str(),
+      CommandTree::NonTerminal {name, ..} => name.as_str(),
+      CommandTree::Top(_) => "",
+    }
+  }
+  pub fn get_help(&self) -> &str {
+    match self {
+      CommandTree::Terminal { help_msg, ..} => help_msg.as_ref().map(|s| s.as_str()).unwrap_or("<no help text provided>"),
+      CommandTree::NonTerminal { help_msg, .. } => help_msg.as_ref().map(|s| s.as_str()).unwrap_or("<no help text provided>"),
+      CommandTree::Top(_) => ""
+    }
+  }
+  pub fn get_children(&self) -> &Vec<CommandTree> {
+    use CommandTree::*;
+    match self {
+      Terminal { children, .. } |
+      NonTerminal { children, .. } |
+      Top(children) => children
+    }
+  }
+  pub fn get_subcommands(&self) -> Vec<&str> {
+    self.get_children().iter().map(|x| x.get_cmd()).collect()
+  }
+
+  pub fn perform(&self, repl: &mut Repl, arguments: &Vec<&str>) -> InterpreterDirectiveOutput {
+    let mut dir_pointer: &CommandTree = self;
+    let mut idx = 0;
+
+    let res: Result<(DirectiveAction, usize), String> = loop {
+      match dir_pointer {
+        CommandTree::Top(subcommands) | CommandTree::NonTerminal { children: subcommands, .. } => {
+          let next_command = match arguments.get(idx) {
+            Some(cmd) => cmd,
+            None => break Err(format!("Command requires arguments"))
+          };
+          idx += 1;
+          match subcommands.iter().find(|sc| sc.get_cmd() == *next_command) {
+            Some(command_tree) => {
+              dir_pointer = command_tree;
+            },
+            None => break Err(format!("Command {} not found", next_command))
+          };
+        },
+        CommandTree::Terminal { action, .. } => {
+          break Ok((action.clone(), idx));
+        },
+      }
+    };
+
+    match res {
+      Ok((action, idx)) => action.perform(repl, &arguments[idx..]),
+      Err(err) => Some(err.red().to_string())
+    }
+  }
+}
--- a/schala-repl/src/repl/directive_actions.rs
+++ b/schala-repl/src/repl/directive_actions.rs
@ -0,0 +1,133 @@
+use super::{Repl, InterpreterDirectiveOutput};
+use crate::repl::help::help;
+use crate::language::{LangMetaRequest, LangMetaResponse, DebugAsk, DebugResponse}; 
+use itertools::Itertools;
+use std::fmt::Write as FmtWrite;
+
+#[derive(Debug, Clone)]
+pub enum DirectiveAction {
+  Null,
+  Help,
+  QuitProgram,
+  ListPasses,
+  ShowImmediate,
+  Show,
+  Hide,
+  TotalTimeOff,
+  TotalTimeOn,
+  StageTimeOff,
+  StageTimeOn,
+  Doc,
+}
+
+impl DirectiveAction {
+  pub fn perform(&self, repl: &mut Repl, arguments: &[&str]) -> InterpreterDirectiveOutput {
+    use DirectiveAction::*;
+    match self {
+      Null => None,
+      Help => help(repl, arguments),
+      QuitProgram => {
+        repl.save_before_exit();
+        ::std::process::exit(0)
+      },
+      ListPasses => {
+        let language_state = repl.get_cur_language_state();
+        let pass_names = match language_state.request_meta(LangMetaRequest::StageNames) {
+          LangMetaResponse::StageNames(names) => names,
+          _ => vec![],
+        };
+
+        let mut buf = String::new();
+        for pass in pass_names.iter().map(|name| Some(name)).intersperse(None) {
+          match pass {
+            Some(pass) => write!(buf, "{}", pass).unwrap(),
+            None => write!(buf, " -> ").unwrap(),
+          }
+        }
+        Some(buf)
+      },
+      ShowImmediate => {
+        let cur_state = repl.get_cur_language_state();
+        let stage_name = match arguments.get(0) {
+          Some(s) => s.to_string(),
+          None => return Some(format!("Must specify a thing to debug")),
+        };
+        let meta = LangMetaRequest::ImmediateDebug(DebugAsk::ByStage { stage_name: stage_name.clone(), token: None });
+        let meta_response = cur_state.request_meta(meta);
+
+        let response = match meta_response {
+          LangMetaResponse::ImmediateDebug(DebugResponse { ask, value }) => match  ask {
+            DebugAsk::ByStage { stage_name: ref this_stage_name, ..} if *this_stage_name == stage_name => value,
+            _ => return Some(format!("Wrong debug stage"))
+          },
+          _ => return Some(format!("Invalid language meta response")),
+        };
+        Some(response)
+      },
+      Show => {
+        let this_stage_name = match arguments.get(0) {
+          Some(s) => s.to_string(),
+          None => return Some(format!("Must specify a stage to show")),
+        };
+        let token = arguments.get(1).map(|s| s.to_string());
+        repl.options.debug_asks.retain(|ask| match ask {
+          DebugAsk::ByStage { stage_name, .. } if *stage_name == this_stage_name => false,
+          _ => true
+        });
+
+        let ask = DebugAsk::ByStage { stage_name: this_stage_name, token };
+        repl.options.debug_asks.insert(ask);
+        None
+      },
+      Hide => {
+        let stage_name_to_remove = match arguments.get(0) {
+          Some(s) => s.to_string(),
+          None => return Some(format!("Must specify a stage to hide")),
+        };
+        repl.options.debug_asks.retain(|ask| match ask {
+          DebugAsk::ByStage { stage_name, .. } if *stage_name == stage_name_to_remove => false,
+          _ => true
+        });
+        None
+      },
+      TotalTimeOff => total_time_off(repl, arguments),
+      TotalTimeOn => total_time_on(repl, arguments),
+      StageTimeOff => stage_time_off(repl, arguments),
+      StageTimeOn => stage_time_on(repl, arguments),
+      Doc => doc(repl, arguments),
+    }
+  }
+}
+
+fn total_time_on(repl: &mut Repl, _: &[&str]) -> InterpreterDirectiveOutput {
+  repl.options.show_total_time = true;
+  None
+}
+
+fn total_time_off(repl: &mut Repl, _: &[&str]) -> InterpreterDirectiveOutput {
+  repl.options.show_total_time = false;
+  None
+}
+
+fn stage_time_on(repl: &mut Repl, _: &[&str]) -> InterpreterDirectiveOutput {
+  repl.options.show_stage_times = true;
+  None
+}
+
+fn stage_time_off(repl: &mut Repl, _: &[&str]) -> InterpreterDirectiveOutput {
+  repl.options.show_stage_times = false;
+  None
+}
+
+fn doc(repl: &mut Repl, arguments: &[&str]) -> InterpreterDirectiveOutput {
+  arguments.get(0).map(|cmd| {
+    let source = cmd.to_string();
+    let meta = LangMetaRequest::Docs { source };
+    let cur_state = repl.get_cur_language_state();
+    match cur_state.request_meta(meta) {
+      LangMetaResponse::Docs { doc_string } => Some(doc_string),
+      _ => Some(format!("Invalid doc response"))
+    }
+  }).unwrap_or(Some(format!(":docs needs an argument")))
+}
+
--- a/schala-repl/src/repl/directives.rs
+++ b/schala-repl/src/repl/directives.rs
@ -0,0 +1,55 @@
+use crate::repl::command_tree::CommandTree;
+use crate::repl::directive_actions::DirectiveAction;
+
+pub fn directives_from_pass_names(pass_names: &Vec<String>) -> CommandTree {
+  let passes_directives: Vec<CommandTree> = pass_names.iter()
+    .map(|pass_name| {
+      if pass_name == "parsing" {
+        CommandTree::nonterm(pass_name, None, vec![
+          CommandTree::nonterm_no_further_tab_completions("compact", None),
+          CommandTree::nonterm_no_further_tab_completions("expanded", None),
+          CommandTree::nonterm_no_further_tab_completions("trace", None),
+        ])
+      } else {
+        CommandTree::nonterm_no_further_tab_completions(pass_name, None) 
+      }
+    })
+    .collect();
+  CommandTree::Top(get_list(&passes_directives, true))
+}
+
+fn get_list(passes_directives: &Vec<CommandTree>, include_help: bool) -> Vec<CommandTree> {
+  use DirectiveAction::*;
+
+  vec![
+    CommandTree::terminal("exit", Some("exit the REPL"), vec![], QuitProgram),
+    CommandTree::terminal("quit", Some("exit the REPL"), vec![], QuitProgram),
+    CommandTree::terminal("help", Some("Print this help message"), if include_help { get_list(passes_directives, false) } else { vec![] }, Help),
+    CommandTree::nonterm("debug",
+      Some("Configure debug information"),
+      vec![
+        CommandTree::terminal("list-passes", Some("List all registered compiler passes"), vec![], ListPasses),
+        CommandTree::terminal("show-immediate", None, passes_directives.clone(), ShowImmediate),
+        CommandTree::terminal("show", Some("Show debug output for a specific pass"), passes_directives.clone(), Show),
+        CommandTree::terminal("hide", Some("Hide debug output for a specific pass"), passes_directives.clone(), Hide),
+        CommandTree::nonterm("total-time", None, vec![
+          CommandTree::terminal("on", None, vec![], TotalTimeOn), 
+          CommandTree::terminal("off", None, vec![], TotalTimeOff),
+        ]),
+        CommandTree::nonterm("stage-times", Some("Computation time per-stage"), vec![
+          CommandTree::terminal("on", None, vec![], StageTimeOn),
+          CommandTree::terminal("off", None, vec![], StageTimeOff),
+        ])
+      ]
+    ),
+    CommandTree::nonterm("lang",
+      Some("switch between languages, or go directly to a langauge by name"),
+      vec![
+        CommandTree::nonterm_no_further_tab_completions("next", None),
+        CommandTree::nonterm_no_further_tab_completions("prev", None),
+        CommandTree::nonterm("go", None, vec![]),
+      ]
+    ),
+    CommandTree::terminal("doc", Some("Get language-specific help for an item"), vec![], Doc),
+  ]
+}
--- a/schala-repl/src/repl/help.rs
+++ b/schala-repl/src/repl/help.rs
@ -0,0 +1,59 @@
+use std::fmt::Write as FmtWrite;
+
+use colored::*;
+use super::command_tree::CommandTree;
+use super::{Repl, InterpreterDirectiveOutput};
+
+pub fn help(repl: &mut Repl, arguments: &[&str]) -> InterpreterDirectiveOutput {
+  match arguments {
+    [] =>  return global_help(repl),
+    commands => {
+      let dirs = repl.get_directives();
+      Some(match get_directive_from_commands(commands, &dirs) {
+        None => format!("Directive `{}` not found", commands.last().unwrap()),
+        Some(dir) => {
+          let mut buf = String::new();
+          let cmd = dir.get_cmd();
+          let children = dir.get_children();
+          writeln!(buf, "`{}` - {}", cmd, dir.get_help()).unwrap();
+          for sub in children.iter() {
+            writeln!(buf, "\t`{} {}` - {}", cmd, sub.get_cmd(), sub.get_help()).unwrap();
+          }
+          buf
+        }
+      })
+    }
+  }
+}
+
+fn get_directive_from_commands<'a>(commands: &[&str], dirs: &'a CommandTree) -> Option<&'a CommandTree> {
+  let mut directive_list = dirs.get_children();
+  let mut matched_directive = None;
+  for cmd in commands {
+    let found = directive_list.iter().find(|directive| directive.get_cmd() == *cmd);
+    if let Some(dir) = found {
+      directive_list = dir.get_children();
+    }
+
+    matched_directive = found;
+  }
+  matched_directive
+}
+
+fn global_help(repl: &mut Repl) -> InterpreterDirectiveOutput {
+  let mut buf = String::new();
+  let sigil = repl.interpreter_directive_sigil;
+
+  writeln!(buf, "{} version {}", "Schala REPL".bright_red().bold(), crate::VERSION_STRING).unwrap();
+  writeln!(buf, "-----------------------").unwrap();
+
+  for directive in repl.get_directives().get_children() {
+    writeln!(buf, "{}{} - {}", sigil, directive.get_cmd(), directive.get_help()).unwrap();
+  }
+
+  let ref lang = repl.get_cur_language_state();
+  writeln!(buf, "").unwrap();
+  writeln!(buf, "Language-specific help for {}", lang.get_language_name()).unwrap();
+  writeln!(buf, "-----------------------").unwrap();
+  Some(buf)
+}
--- a/schala-repl/src/repl/mod.rs
+++ b/schala-repl/src/repl/mod.rs
@ -0,0 +1,251 @@
+use std::sync::Arc;
+use std::collections::HashSet;
+
+use crate::language::{ProgrammingLanguageInterface,
+ComputationRequest, LangMetaResponse, LangMetaRequest};
+
+mod command_tree;
+use self::command_tree::CommandTree;
+mod repl_options;
+use repl_options::ReplOptions;
+mod directive_actions;
+mod directives;
+use directives::directives_from_pass_names;
+mod help;
+mod response;
+use response::ReplResponse;
+
+const HISTORY_SAVE_FILE: &'static str = ".schala_history";
+const OPTIONS_SAVE_FILE: &'static str = ".schala_repl";
+
+type InterpreterDirectiveOutput = Option<String>;
+
+pub struct Repl {
+  pub interpreter_directive_sigil: char,
+  line_reader: ::linefeed::interface::Interface<::linefeed::terminal::DefaultTerminal>,
+  language_states: Vec<Box<dyn ProgrammingLanguageInterface>>,
+  options: ReplOptions,
+}
+
+#[derive(Clone)]
+enum PromptStyle {
+  Normal,
+  Multiline
+}
+
+impl Repl {
+  pub fn new(initial_states: Vec<Box<dyn ProgrammingLanguageInterface>>) -> Repl {
+    use linefeed::Interface;
+    let line_reader = Interface::new("schala-repl").unwrap();
+    let interpreter_directive_sigil = ':';
+
+    Repl {
+      interpreter_directive_sigil,
+      line_reader,
+      language_states: initial_states,
+      options: ReplOptions::new(),
+    }
+  }
+
+  pub fn run_repl(&mut self) {
+    println!("Schala MetaInterpreter version {}", crate::VERSION_STRING);
+    println!("Type {}help for help with the REPL", self.interpreter_directive_sigil);
+    self.load_options();
+    self.handle_repl_loop();
+    self.save_before_exit();
+    println!("Exiting...");
+  }
+
+  fn load_options(&mut self) {
+    self.line_reader.load_history(HISTORY_SAVE_FILE).unwrap_or(());
+    match ReplOptions::load_from_file(OPTIONS_SAVE_FILE) {
+      Ok(options) => {
+        self.options = options;
+      },
+      Err(()) => ()
+    };
+  }
+
+  fn handle_repl_loop(&mut self) {
+    use linefeed::ReadResult::*;
+    let sigil = self.interpreter_directive_sigil;
+
+    'main: loop {
+      macro_rules! match_or_break {
+        ($line:expr) => {
+          match $line {
+            Err(e) => {
+              println!("readline IO Error: {}", e);
+              break 'main;
+            },
+            Ok(Eof) | Ok(Signal(_)) => break 'main,
+            Ok(Input(ref input)) => input,
+          }
+        }
+      }
+      self.update_line_reader();
+      let line = self.line_reader.read_line();
+      let input: &str = match_or_break!(line);
+
+      self.line_reader.add_history_unique(input.to_string());
+      let mut chars = input.chars().peekable();
+      let repl_responses = match chars.nth(0) {
+        Some(ch) if ch == sigil => {
+          if chars.peek() == Some(&'{') {
+            let mut buf = String::new();
+            buf.push_str(input.get(2..).unwrap());
+            'multiline: loop {
+              self.set_prompt(PromptStyle::Multiline);
+              let new_line = self.line_reader.read_line();
+              let new_input = match_or_break!(new_line);
+              if new_input.starts_with(":}") {
+                break 'multiline;
+              } else {
+                buf.push_str(new_input);
+                buf.push_str("\n");
+              }
+            }
+            self.handle_input(&buf)
+          } else {
+            match self.handle_interpreter_directive(input) {
+              Some(directive_output) => println!("<> {}", directive_output),
+              None => (),
+            }
+            continue
+          }
+        },
+        _ => self.handle_input(input)
+      };
+
+      for repl_response in repl_responses.iter() {
+        println!("{}", repl_response);
+      }
+    }
+  }
+
+  fn update_line_reader(&mut self) {
+    let tab_complete_handler = TabCompleteHandler::new(self.interpreter_directive_sigil, self.get_directives());
+    self.line_reader.set_completer(Arc::new(tab_complete_handler)); //TODO fix this here
+    self.set_prompt(PromptStyle::Normal);
+  }
+
+  fn set_prompt(&mut self, prompt_style: PromptStyle) {
+    let prompt_str = match prompt_style {
+      PromptStyle::Normal => ">> ".to_string(),
+      PromptStyle::Multiline => ">| ".to_string(),
+    };
+
+    self.line_reader.set_prompt(&prompt_str).unwrap();
+  }
+
+  fn save_before_exit(&self) {
+    self.line_reader.save_history(HISTORY_SAVE_FILE).unwrap_or(());
+    self.options.save_to_file(OPTIONS_SAVE_FILE);
+  }
+
+  fn handle_interpreter_directive(&mut self, input: &str) -> InterpreterDirectiveOutput {
+    let mut iter = input.chars();
+    iter.next();
+    let arguments: Vec<&str> = iter
+      .as_str()
+      .split_whitespace()
+      .collect();
+
+    if arguments.len() < 1 {
+      return None;
+    }
+
+    let directives = self.get_directives();
+    directives.perform(self, &arguments)
+  }
+
+  fn get_cur_language_state(&mut self) -> &mut Box<dyn ProgrammingLanguageInterface> {
+    //TODO this is obviously not complete
+    &mut self.language_states[0]
+  }
+
+  fn handle_input(&mut self, input: &str) -> Vec<ReplResponse> {
+    let mut debug_requests = HashSet::new();
+    for ask in self.options.debug_asks.iter() {
+      debug_requests.insert(ask.clone());
+    }
+
+    let request = ComputationRequest { source: input, debug_requests };
+    let ref mut language_state = self.get_cur_language_state();
+    let response = language_state.run_computation(request);
+    response::handle_computation_response(response, &self.options)
+  }
+
+  fn get_directives(&mut self) -> CommandTree {
+    let language_state = self.get_cur_language_state();
+    let pass_names = match language_state.request_meta(LangMetaRequest::StageNames) {
+      LangMetaResponse::StageNames(names) => names,
+      _ => vec![],
+    };
+
+    directives_from_pass_names(&pass_names)
+  }
+}
+
+
+struct TabCompleteHandler {
+  sigil: char,
+  top_level_commands: CommandTree,
+}
+
+use linefeed::complete::{Completion, Completer};
+use linefeed::terminal::Terminal;
+
+impl TabCompleteHandler {
+  fn new(sigil: char, top_level_commands: CommandTree) -> TabCompleteHandler {
+    TabCompleteHandler {
+      top_level_commands,
+      sigil,
+    }
+  }
+}
+
+impl<T: Terminal> Completer<T> for TabCompleteHandler {
+  fn complete(&self, word: &str, prompter: &::linefeed::prompter::Prompter<T>, start: usize, _end: usize) -> Option<Vec<Completion>> {
+    let line = prompter.buffer();
+
+    if !line.starts_with(self.sigil) {
+      return None;
+    }
+
+    let mut words = line[1..(if start == 0 { 1 } else { start })].split_whitespace();
+    let mut completions = Vec::new();
+    let mut command_tree: Option<&CommandTree> = Some(&self.top_level_commands);
+
+    loop {
+      match words.next() {
+        None => {
+          let top = match command_tree {
+            Some(CommandTree::Top(_)) => true,
+            _ => false
+          };
+          let word = if top { word.get(1..).unwrap() } else { word };
+          for cmd in command_tree.map(|x| x.get_subcommands()).unwrap_or(vec![]).into_iter() {
+            if cmd.starts_with(word) {
+              completions.push(Completion {
+                completion: format!("{}{}", if top { ":" } else { "" }, cmd),
+                display: Some(cmd.to_string()),
+                suffix: ::linefeed::complete::Suffix::Some(' ')
+              })
+            }
+          }
+          break;
+        },
+        Some(s) => {
+          let new_ptr: Option<&CommandTree> = command_tree.and_then(|cm| match cm {
+            CommandTree::Top(children) => children.iter().find(|c| c.get_cmd() == s),
+            CommandTree::NonTerminal { children, .. } => children.iter().find(|c| c.get_cmd() == s),
+            CommandTree::Terminal { children, .. } => children.iter().find(|c| c.get_cmd() == s),
+          });
+          command_tree = new_ptr;
+        }
+      }
+    }
+    Some(completions)
+  }
+}
--- a/schala-repl/src/repl/repl_options.rs
+++ b/schala-repl/src/repl/repl_options.rs
@ -0,0 +1,47 @@
+use crate::language::DebugAsk;
+
+use std::io::{Read, Write};
+use std::collections::HashSet;
+use std::fs::File;
+
+#[derive(Serialize, Deserialize)]
+pub struct ReplOptions {
+  pub debug_asks: HashSet<DebugAsk>,
+  pub show_total_time: bool,
+  pub show_stage_times: bool,
+}
+
+impl ReplOptions {
+  pub fn new() -> ReplOptions {
+    ReplOptions {
+      debug_asks: HashSet::new(),
+      show_total_time: true,
+      show_stage_times: false,
+    }
+  }
+
+  pub fn save_to_file(&self, filename: &str) {
+    let res = File::create(filename)
+      .and_then(|mut file| {
+        let buf = crate::serde_json::to_string(self).unwrap();
+        file.write_all(buf.as_bytes())
+      });
+    if let Err(err) = res {
+      println!("Error saving {} file {}", filename, err);
+    }
+  }
+
+  pub fn load_from_file(filename: &str) -> Result<ReplOptions, ()> {
+    File::open(filename)
+      .and_then(|mut file| {
+        let mut contents = String::new();
+        file.read_to_string(&mut contents)?;
+        Ok(contents)
+      })
+    .and_then(|contents| {
+      let output: ReplOptions = crate::serde_json::from_str(&contents)?;
+      Ok(output)
+    })
+    .map_err(|_| ())
+  }
+}
--- a/schala-repl/src/repl/response.rs
+++ b/schala-repl/src/repl/response.rs
@ -0,0 +1,67 @@
+use colored::*;
+use std::fmt;
+use std::fmt::Write;
+
+use super::ReplOptions;
+use crate::language::{ DebugAsk, ComputationResponse};
+
+pub struct ReplResponse {
+  label: Option<String>,
+  text: String,
+  color: Option<Color>
+}
+
+impl fmt::Display for ReplResponse {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    let mut buf = String::new();
+    if let Some(ref label) = self.label {
+      write!(buf, "({})", label).unwrap();
+    }
+    write!(buf, "=> {}", self.text).unwrap();
+    write!(f, "{}", match self.color {
+      Some(c) => buf.color(c),
+      None => buf.normal()
+    })
+  }
+}
+
+
+pub fn handle_computation_response(response: ComputationResponse, options: &ReplOptions) -> Vec<ReplResponse> {
+  let mut responses = vec![];
+
+  if options.show_total_time {
+    responses.push(ReplResponse {
+      label: Some("Total time".to_string()),
+      text: format!("{:?}", response.global_output_stats.total_duration),
+      color: None,
+    });
+  }
+
+  if options.show_stage_times {
+    responses.push(ReplResponse {
+      label: Some("Stage times".to_string()),
+      text: format!("{:?}", response.global_output_stats.stage_durations),
+      color: None,
+    });
+  }
+
+  for debug_resp in response.debug_responses {
+    let stage_name = match debug_resp.ask {
+      DebugAsk::ByStage { stage_name, .. } => stage_name,
+      _ => continue,
+    };
+    responses.push(ReplResponse {
+      label: Some(stage_name.to_string()),
+      text: debug_resp.value,
+      color: Some(Color::Red),
+    });
+  }
+
+  responses.push(match response.main_output {
+    Ok(s) => ReplResponse { label: None, text: s, color: None },
+    Err(e) => ReplResponse { label: Some("Error".to_string()), text: e, color: Some(Color::Red) },
+  });
+
+  responses
+}
+
--- a/schala-repl/src/repl_options.rs
+++ b/schala-repl/src/repl_options.rs
@ -1,43 +0,0 @@
-use std::{
-    collections::HashSet,
-    fs::File,
-    io::{self, Read, Write},
-};
-
-use crate::language::DebugAsk;
-
-#[derive(Serialize, Deserialize)]
-pub struct ReplOptions {
-    pub debug_asks: HashSet<DebugAsk>,
-    pub show_total_time: bool,
-    pub show_stage_times: bool,
-}
-
-impl ReplOptions {
-    pub fn new() -> ReplOptions {
-        ReplOptions { debug_asks: HashSet::new(), show_total_time: true, show_stage_times: false }
-    }
-
-    pub fn save_to_file(&self, filename: &str) {
-        let res = File::create(filename).and_then(|mut file| {
-            let buf = crate::serde_json::to_string(self).unwrap();
-            file.write_all(buf.as_bytes())
-        });
-        if let Err(err) = res {
-            eprintln!("Error saving {} file {}", filename, err);
-        }
-    }
-
-    pub fn load_from_file(filename: &str) -> Result<ReplOptions, io::Error> {
-        File::open(filename)
-            .and_then(|mut file| {
-                let mut contents = String::new();
-                file.read_to_string(&mut contents)?;
-                Ok(contents)
-            })
-            .and_then(|contents| {
-                let output: ReplOptions = crate::serde_json::from_str(&contents)?;
-                Ok(output)
-            })
-    }
-}
--- a/schala-repl/src/response.rs
+++ b/schala-repl/src/response.rs
@ -1,74 +0,0 @@
-use std::{fmt, fmt::Write};
-
-use colored::*;
-
-use crate::{
-    language::{ComputationResponse, DebugAsk},
-    ReplOptions,
-};
-
-pub struct ReplResponse {
-    label: Option<String>,
-    text: String,
-    color: Option<Color>,
-}
-
-impl fmt::Display for ReplResponse {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let mut buf = String::new();
-        if let Some(ref label) = self.label {
-            write!(buf, "({})", label).unwrap();
-        }
-        write!(buf, "=> {}", self.text).unwrap();
-        write!(
-            f,
-            "{}",
-            match self.color {
-                Some(c) => buf.color(c),
-                None => buf.normal(),
-            }
-        )
-    }
-}
-
-pub fn handle_computation_response(
-    response: ComputationResponse,
-    options: &ReplOptions,
-) -> Vec<ReplResponse> {
-    let mut responses = vec![];
-
-    if options.show_total_time {
-        responses.push(ReplResponse {
-            label: Some("Total time".to_string()),
-            text: format!("{:?}", response.global_output_stats.total_duration),
-            color: None,
-        });
-    }
-
-    if options.show_stage_times {
-        responses.push(ReplResponse {
-            label: Some("Stage times".to_string()),
-            text: format!("{:?}", response.global_output_stats.stage_durations),
-            color: None,
-        });
-    }
-
-    for debug_resp in response.debug_responses {
-        let stage_name = match debug_resp.ask {
-            DebugAsk::ByStage { stage_name, .. } => stage_name,
-            _ => continue,
-        };
-        responses.push(ReplResponse {
-            label: Some(stage_name.to_string()),
-            text: debug_resp.value,
-            color: Some(Color::Red),
-        });
-    }
-
-    responses.push(match response.main_output {
-        Ok(s) => ReplResponse { label: None, text: s, color: None },
-        Err(e) => ReplResponse { label: Some("Error".to_string()), text: e, color: Some(Color::Red) },
-    });
-
-    responses
-}
--- a/source_files/schala/syntax_playground.schala
+++ b/source_files/schala/syntax_playground.schala
@ -6,37 +6,36 @@ fn main() {

 }

-
-@annotations use the @ sigil
+@annotations are with @-

 // variable expressions
-  //variable declaration works like Rust
-  let a: I32 = 20
-  let mut b: String = 20
+  var a: I32 = 20
+  const b: String = 20

  there(); can(); be(); multiple(); statements(); per_line();

  //string interpolation
-  // maybe
-  let yolo = "I have ${a + b} people in my house"
+  const yolo = "I have ${a + b} people in my house"

-  // let expressions
+  // let expressions ??? not sure if I want this
  let a = 10, b = 20, c = 30 in a + b + c

  //list literal
-  let q = [1,2,3,4]
+  const q = [1,2,3,4]

-  //lambda literal - uses haskell-ish syntax
-  q.map(\(item) { item * 100 })
+  //lambda literal 
+  q.map({|item| item * 100 })

  fn yolo(a: MyType, b: YourType): ReturnType<Param1, Param2> {
    if a == 20 {
      return "early"
    }
+    var sex = 20
+    sex
  }

+
 /* for/while loop topics */
-//TODO I can probably get away with having one of `for`, `while`

   //infinite loop
   while {
@ -60,7 +59,7 @@ fn main() {
  //monadic decomposition
  for {
    a <- maybeInt();
-    s <- foo()
+    s <- foo() 
  } return {
    a + s
  } //return type is Monad<return type of block>
@ -71,13 +70,13 @@ fn main() {

 /* conditionals/pattern matching */

-// `is` functions as an operator asking "does this pattern match"
+// "is" operator for "does this pattern match"

 x is Some(t) // type bool

 if x {
  is Some(t) => {
-  }
+  },
  is None => {

  }
@ -87,7 +86,7 @@ if x {
 //syntax is, I guess, for <expr> <brace-block>, where <expr> is a bool, or a <arrow-expr>

 // type level alises
- type alias <name> = <other type> #maybe thsi should be 'alias'?
+ typealias <name> = <other type> #maybe thsi should be 'alias'?

 /*
 what if type A = B meant that you could had to create A's with A(B), but when you used A's the interface was exactly like B's?
@ -95,12 +94,12 @@ what if type A = B meant that you could had to create A's with A(B), but when yo
 */

 //declaring types of all stripes
- type MyData = { a: i32, b: String } // shorthand special-case for `type MyData = MyData { a: i32, b: String }`
+ type MyData = { a: i32, b: String }
 type MyType = MyType
 type Option<a> = None | Some(a)
 type Signal = Absence | SimplePresence(i32) | ComplexPresence {a: i32, b: MyCustomData}

- //traits TODO I probably want to rename this
+ //traits
 
 trait Bashable { }
 trait Luggable {
@ -109,7 +108,7 @@ what if type A = B meant that you could had to create A's with A(B), but when yo

 }

-// lambdas - maybe I want to use ruby-style (not rust style) syntax
-// e.g.
-// Also TODO Nix uses `X: Y: Z` for in its value-level syntax, why can't I?
-let a: X -> Y -> Z = {|x,y|  }
+
+// lambdas
+// ruby-style not rust-style
+const a: X -> Y -> Z = {|x,y|  }
--- a/src/main.rs
+++ b/src/main.rs
@ -1,71 +1,15 @@
-use std::{collections::HashSet, fs::File, io::Read, path::PathBuf, process::exit};
+extern crate schala_repl;

-use schala_lang::{Schala, SchalaConfig};
-use schala_repl::{ComputationRequest, ProgrammingLanguageInterface, Repl};
+//extern crate maaru_lang;
+//extern crate rukka_lang;
+//extern crate robo_lang;
+extern crate schala_lang;
+use schala_repl::{ProgrammingLanguageInterface, start_repl};
+
+extern { }

-//TODO specify multiple langs, and have a way to switch between them
 fn main() {
-    let args: Vec<String> = std::env::args().collect();
-    let matches = command_line_options().parse(&args[1..]).unwrap_or_else(|e| {
-        eprintln!("Error parsing options: {}", e);
-        exit(1);
-    });
-
-    if matches.opt_present("help") {
-        println!("{}", command_line_options().usage("Schala metainterpreter"));
-        exit(0);
-    }
-
-    if matches.free.is_empty() {
-        let state = Schala::new();
-        let mut repl = Repl::new(state);
-        let config = SchalaConfig { repl: true };
-        repl.run_repl(config);
-    } else {
-        let paths: Vec<PathBuf> = matches.free.iter().map(PathBuf::from).collect();
-        //TODO handle more than one file
-        let filename = &paths[0];
-        let extension = filename.extension().and_then(|e| e.to_str()).unwrap_or_else(|| {
-            eprintln!("Source file `{}` has no extension.", filename.display());
-            exit(1);
-        });
-
-        //TODO this proably should be a macro for every supported language
-        if extension == Schala::source_file_suffix() {
-            let config = SchalaConfig { repl: false };
-
-            run_noninteractive(paths, Schala::new(), config);
-        } else {
-            eprintln!("Extension .{} not recognized", extension);
-            exit(1);
-        }
-    }
+  let langs: Vec<Box<dyn ProgrammingLanguageInterface>> = vec![Box::new(schala_lang::Schala::new())];
+  start_repl(langs);
 }

-pub fn run_noninteractive<L: ProgrammingLanguageInterface>(
-    filenames: Vec<PathBuf>,
-    mut language: L,
-    config: L::Config,
-) {
-    // for now, ony do something with the first filename
-
-    let filename = &filenames[0];
-    let mut source_file = File::open(filename).unwrap();
-    let mut buffer = String::new();
-    source_file.read_to_string(&mut buffer).unwrap();
-
-    let request = ComputationRequest { source: &buffer, config, debug_requests: HashSet::new() };
-
-    let response = language.run_computation(request);
-    match response.main_output {
-        Ok(s) => println!("{}", s),
-        Err(s) => eprintln!("{}", s),
-    };
-}
-
-fn command_line_options() -> getopts::Options {
-    let mut options = getopts::Options::new();
-    options.optflag("h", "help", "Show help text");
-    //options.optflag("w", "webapp", "Start up web interpreter");
-    options
-}