Add note

WIP

.gitignore

@@ -1,3 +1,5 @@
 Cargo.lock
 target
 .schala_repl
+.schala_history
+rusty-tags.vi

Cargo.toml

@@ -5,18 +5,14 @@ authors = ["greg <greg.shuflin@protonmail.com>"]
 
 [dependencies]
 
-llvm-sys = "*"
-take_mut = "0.1.3"
-itertools = "0.5.8"
-getopts = "*"
-linefeed = "0.2.2"
-lazy_static = "0.2.8"
-maplit = "*"
-colored = "1.5"
-serde = "1.0.15"
-serde_derive = "1.0.15"
-serde_json = "1.0.3"
-rocket = "*"
-rocket_codegen = "*"
-rocket_contrib = "*"
+schala-repl = { path = "schala-repl" }
+schala-codegen = { path = "schala-codegen" }
+maaru-lang = { path = "maaru" }
+rukka-lang = { path = "rukka" }
+robo-lang = { path = "robo" }
+schala-lang = { path = "schala-lang" }
 
+[build-dependencies]
+includedir_codegen = "0.2.0"
+
+[workspace]

HindleyMilner.hs

@@ -0,0 +1,920 @@
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE LambdaCase                 #-}
+{-# LANGUAGE OverloadedLists            #-}
+{-# LANGUAGE OverloadedStrings          #-}
+
+
+
+-- | This module is an extensively documented walkthrough for typechecking a
+-- basic functional language using the Hindley-Damas-Milner algorithm.
+--
+-- In the end, we'll be able to infer the type of expressions like
+--
+-- @
+-- find (λx. (>) x 0)
+--   :: [Integer] -> Either () Integer
+-- @
+--
+-- It can be used in multiple different forms:
+--
+--  * The source is written in literate programming style, so you can almost
+--    read it from top to bottom, minus some few references to later topics.
+--  * /Loads/ of doctests (runnable and verified code examples) are included
+--  * The code is runnable in GHCi, all definitions are exposed.
+--  * A small main module that gives many examples of what you might try out in
+--    GHCi is also included.
+--  * The Haddock output yields a nice overview over the definitions given, with
+--    a nice rendering of a truckload of Haddock comments.
+
+module HindleyMilner where
+
+import           Control.Monad.Trans
+import           Control.Monad.Trans.Except
+import           Control.Monad.Trans.State
+import           Data.Map                   (Map)
+import qualified Data.Map                   as M
+import           Data.Monoid
+import           Data.Set                   (Set)
+import qualified Data.Set                   as S
+import           Data.String
+import           Data.Text                  (Text)
+import qualified Data.Text                  as T
+
+
+
+-- $setup
+--
+-- For running doctests:
+--
+-- >>> :set -XOverloadedStrings
+-- >>> :set -XOverloadedLists
+-- >>> :set -XLambdaCase
+-- >>> import qualified Data.Text.IO as T
+-- >>> let putPprLn = T.putStrLn . ppr
+
+
+
+-- #############################################################################
+-- #############################################################################
+-- * Preliminaries
+-- #############################################################################
+-- #############################################################################
+
+
+
+-- #############################################################################
+-- ** Prettyprinting
+-- #############################################################################
+
+
+
+-- | A prettyprinter class. Similar to 'Show', but with a focus on having
+-- human-readable output as opposed to being valid Haskell.
+class Pretty a where
+    ppr :: a -> Text
+
+
+
+-- #############################################################################
+-- ** Names
+-- #############################################################################
+
+
+
+-- | A 'name' is an identifier in the language we're going to typecheck.
+-- Variables on both the term and type level have 'Name's, for example.
+newtype Name = Name Text
+    deriving (Eq, Ord, Show)
+
+-- | >>> "lorem" :: Name
+-- Name "lorem"
+instance IsString Name where
+    fromString = Name . T.pack
+
+-- | >>> putPprLn (Name "var")
+-- var
+instance Pretty Name where
+    ppr (Name n) = n
+
+
+
+-- #############################################################################
+-- ** Monotypes
+-- #############################################################################
+
+
+
+-- | A monotype is an unquantified/unparametric type, in other words it contains
+-- no @forall@s. Monotypes are the inner building blocks of all types. Examples
+-- of monotypes are @Int@, @a@, @a -> b@.
+--
+-- In formal notation, 'MType's are often called τ (tau) types.
+data MType = TVar Name           -- ^ @a@
+           | TFun MType MType    -- ^ @a -> b@
+           | TConst Name         -- ^ @Int@, @()@, …
+
+           -- Since we can't declare our own types in our simple type system
+           -- here, we'll hard-code certain basic ones so we can typecheck some
+           -- familar functions that use them later.
+           | TList MType         -- ^ @[a]@
+           | TEither MType MType -- ^ @Either a b@
+           | TTuple MType MType  -- ^ @(a,b)@
+           deriving Show
+
+-- | >>> putPprLn (TFun (TEither (TVar "a") (TVar "b")) (TFun (TVar "c") (TVar "d")))
+-- Either a b → c → d
+--
+-- Using the 'IsString' instance:
+--
+-- >>> putPprLn (TFun (TEither "a" "b") (TFun "c" "d"))
+-- Either a b → c → d
+instance Pretty MType where
+    ppr = go False
+      where
+        go _ (TVar name)   = ppr name
+        go _ (TList a)     = "[" <> ppr a <> "]"
+        go _ (TEither l r) = "Either " <> ppr l <> " " <> ppr r
+        go _ (TTuple a b)  = "(" <> ppr a <> ", " <> ppr b <> ")"
+        go _ (TConst name) = ppr name
+        go parenthesize (TFun a b)
+            | parenthesize = "(" <> lhs <> " → " <> rhs <> ")"
+            | otherwise    =        lhs <> " → " <> rhs
+            where lhs = go True a
+                  rhs = go False b
+
+-- | >>> "var" :: MType
+-- TVar (Name "var")
+instance IsString MType where
+    fromString = TVar . fromString
+
+
+
+-- | The free variables of an 'MType'. This is simply the collection of all the
+-- individual type variables occurring inside of it.
+--
+-- __Example:__ The free variables of @a -> b@ are @a@ and @b@.
+freeMType :: MType -> Set Name
+freeMType = \case
+    TVar a      -> [a]
+    TFun a b    -> freeMType a <> freeMType b
+    TList a     -> freeMType a
+    TEither l r -> freeMType l <> freeMType r
+    TTuple a b  -> freeMType a <> freeMType b
+    TConst _    -> []
+
+
+
+-- | Substitute all the contained type variables mentioned in the substitution,
+-- and leave everything else alone.
+instance Substitutable MType where
+    applySubst s = \case
+        TVar a -> let Subst s' = s
+                  in M.findWithDefault (TVar a) a s'
+        TFun f x    -> TFun (applySubst s f) (applySubst s x)
+        TList a     -> TList (applySubst s a)
+        TEither l r -> TEither (applySubst s l) (applySubst s r)
+        TTuple a b  -> TTuple (applySubst s a) (applySubst s b)
+        c@TConst {} -> c
+
+
+
+-- #############################################################################
+-- ** Polytypes
+-- #############################################################################
+
+-- | A polytype is a monotype universally quantified over a number of type
+-- variables. In Haskell, all definitions have polytypes, but since the @forall@
+-- is implicit they look a bit like monotypes, maybe confusingly so. For
+-- example, the type of @1 :: Int@ is actually @forall <nothing>. Int@, and the
+-- type of @id@ is @forall a. a -> a@, although GHC displays it as @a -> a@.
+--
+-- A polytype claims to work "for all imaginable type parameters", very similar
+-- to how a lambda claims to work "for all imaginable value parameters". We can
+-- insert a value into a lambda's parameter to evaluate it to a new value, and
+-- similarly we'll later insert types into a polytype's quantified variables to
+-- gain new types.
+--
+-- __Example:__ in a definition @id :: forall a. a -> a@, the @a@ after the
+-- ∀ ("forall") is the collection of type variables, and @a -> a@ is the 'MType'
+-- quantified over. When we have such an @id@, we also have its specialized
+-- version @Int -> Int@ available. This process will be the topic of the type
+-- inference/unification algorithms.
+--
+-- In formal notation, 'PType's are often called σ (sigma) types.
+--
+-- The purpose of having monotypes and polytypes is that we'd like to only have
+-- universal quantification at the top level, restricting our language to rank-1
+-- polymorphism, where type inferece is total (all types can be inferred) and
+-- simple (only a handful of typing rules). Weakening this constraint would be
+-- easy: if we allowed universal quantification within function types we would
+-- get rank-N polymorphism. Taking it even further to allow it anywhere,
+-- effectively replacing all occurrences of 'MType' with 'PType', yields
+-- impredicative types. Both these extensions make the type system
+-- *significantly* more complex though.
+data PType = Forall (Set Name) MType -- ^ ∀{α}. τ
+
+-- | >>> putPprLn (Forall ["a"] (TFun "a" "a"))
+-- ∀a. a → a
+instance Pretty PType where
+    ppr (Forall qs mType) = "∀" <> pprUniversals <> ". " <> ppr mType
+      where
+        pprUniversals
+          | S.null qs = "∅"
+          | otherwise = (T.intercalate " " . map ppr . S.toList) qs
+
+
+
+-- | The free variables of a 'PType' are the free variables of the contained
+-- 'MType', except those universally quantified.
+--
+-- >>> let sigma = Forall ["a"] (TFun "a" (TFun (TTuple "b" "a") "c"))
+-- >>> putPprLn sigma
+-- ∀a. a → (b, a) → c
+-- >>> let display = T.putStrLn . T.intercalate ", " . foldMap (\x -> [ppr x])
+-- >>> display (freePType sigma)
+-- b, c
+freePType :: PType -> Set Name
+freePType (Forall qs mType) = freeMType mType `S.difference` qs
+
+
+
+-- | Substitute all the free type variables.
+instance Substitutable PType where
+    applySubst (Subst subst) (Forall qs mType) =
+        let qs' = M.fromSet (const ()) qs
+            subst' = Subst (subst `M.difference` qs')
+        in Forall qs (applySubst subst' mType)
+
+
+
+-- #############################################################################
+-- ** The environment
+-- #############################################################################
+
+
+
+-- | The environment consists of all the values available in scope, and their
+-- associated polytypes. Other common names for it include "(typing) context",
+-- and because of the commonly used symbol for it sometimes directly
+-- \"Gamma"/@"Γ"@.
+--
+-- There are two kinds of membership in an environment,
+--
+--   - @∈@: an environment @Γ@ can be viewed as a set of @(value, type)@ pairs,
+--     and we can test whether something is /literally contained/ by it via
+--     x:σ ∈ Γ
+--   - @⊢@, pronounced /entails/, describes all the things that are well-typed,
+--     given an environment @Γ@. @Γ ⊢ x:τ@ can thus be seen as a judgement that
+--     @x:τ@ is /figuratively contained/ in @Γ@.
+--
+-- For example, the environment @{x:Int}@ literally contains @x@, but given
+-- this, it also entails @λy. x@, @λy z. x@, @let id = λy. y in id x@ and so on.
+--
+-- In Haskell terms, the environment consists of all the things you currently
+-- have available, or that can be built by comining them. If you import the
+-- Prelude, your environment entails
+--
+-- @
+-- id            →  ∀a. a→a
+-- map           →  ∀a b. (a→b) → [a] → [b]
+-- putStrLn      →  ∀∅. String → IO ()
+-- …
+-- id map        →  ∀a b. (a→b) → [a] → [b]
+-- map putStrLn  →  ∀∅. [String] -> [IO ()]
+-- …
+-- @
+newtype Env = Env (Map Name PType)
+
+-- | >>> :{
+--    putPprLn (Env
+--        [ ("id", Forall ["a"] (TFun "a" "a"))
+--        , ("const", Forall ["a", "b"] (TFun "a" (TFun "b" "a"))) ])
+-- :}
+-- Γ = { const : ∀a b. a → b → a
+--     , id : ∀a. a → a }
+instance Pretty Env where
+    ppr (Env env) = "Γ = { " <> T.intercalate "\n    , " pprBindings <> " }"
+      where
+        bindings = M.assocs env
+        pprBinding (name, pType) = ppr name <> " : " <> ppr pType
+        pprBindings = map pprBinding bindings
+
+
+
+-- | The free variables of an 'Env'ironment are all the free variables of the
+-- 'PType's it contains.
+freeEnv :: Env -> Set Name
+freeEnv (Env env) = let allPTypes = M.elems env
+                    in S.unions (map freePType allPTypes)
+
+
+
+-- | Performing a 'Subst'itution in an 'Env'ironment means performing that
+-- substituion on all the contained 'PType's.
+instance Substitutable Env where
+    applySubst s (Env env) = Env (M.map (applySubst s) env)
+
+
+
+-- #############################################################################
+-- ** Substitutions
+-- #############################################################################
+
+
+
+-- | A substitution is a mapping from type variables to 'MType's. Applying a
+-- substitution means applying those replacements. For example, the substitution
+-- @a -> Int@ applied to @a -> a@ yields the result @Int -> Int@.
+--
+-- A key concept behind Hindley-Milner is that once we dive deeper into an
+-- expression, we learn more about our type variables. We might learn that  @a@
+-- has to be specialized to @b -> b@, and then later on that @b@ is actually
+-- @Int@. Substitutions are an organized way of carrying this information along.
+newtype Subst = Subst (Map Name MType)
+
+
+
+-- | We're going to apply substitutions to a variety of other values that
+-- somehow contain type variables, so we overload this application operation in
+-- a class here.
+--
+-- Laws:
+--
+-- @
+-- 'applySubst' 'mempty' ≡ 'id'
+-- 'applySubst' (s1 '<>' s2) ≡ 'applySubst' s1 . 'applySubst' s2
+-- @
+class Substitutable a where
+    applySubst :: Subst -> a -> a
+
+instance (Substitutable a, Substitutable b) => Substitutable (a,b) where
+    applySubst s (x,y) = (applySubst s x, applySubst s y)
+
+-- | @'applySubst' s1 s2@ applies one substitution to another, replacing all the
+-- bindings in the second argument @s2@ with their values mentioned in the first
+-- one (@s1@).
+instance Substitutable Subst where
+    applySubst s (Subst target) = Subst (fmap (applySubst s) target)
+
+-- | >>> :{
+--    putPprLn (Subst
+--        [ ("a", TFun "b" "b")
+--        , ("b", TEither "c" "d") ])
+-- :}
+-- { a ––> b → b
+-- , b ––> Either c d }
+instance Pretty Subst where
+    ppr (Subst s) = "{ " <> T.intercalate "\n, " [ ppr k <> " ––> " <> ppr v | (k,v) <- M.toList s ] <> " }"
+
+-- | Combine two substitutions by applying all substitutions mentioned in the
+-- first argument to the type variables contained in the second.
+instance Monoid Subst where
+    -- Considering that all we can really do with a substitution is apply it, we
+    -- can use the one of 'Substitutable's laws to show that substitutions
+    -- combine associatively,
+    --
+    -- @
+    --   applySubst (compose s1 (compose s2 s3))
+    -- = applySubst s1 . applySubst (compose s2 s3)
+    -- = applySubst s1 . applySubst s2 . applySubst s3
+    -- = applySubst (compose s1 s2) . applySubst s3
+    -- = applySubst (compose (compose s1 s2) s3)
+    -- @
+    mappend subst1 subst2 = Subst (s1 `M.union` s2)
+      where
+        Subst s1 = subst1
+        Subst s2 = applySubst subst1 subst2
+
+    mempty = Subst M.empty
+
+
+
+-- #############################################################################
+-- #############################################################################
+-- * Typechecking
+-- #############################################################################
+-- #############################################################################
+
+-- $ Typechecking does two things:
+--
+-- 1. If two types are not immediately identical, attempt to 'unify' them
+--    to get a type compatible with both of them
+-- 2. 'infer' the most general type of a value by comparing the values in its
+--    definition with the 'Env'ironment
+
+
+
+-- #############################################################################
+-- ** Inference context
+-- #############################################################################
+
+
+
+-- | The inference type holds a supply of unique names, and can fail with a
+-- descriptive error if something goes wrong.
+--
+-- /Invariant:/ the supply must be infinite, or we might run out of names to
+-- give to things.
+newtype Infer a = Infer (ExceptT InferError (State [Name]) a)
+    deriving (Functor, Applicative, Monad)
+
+-- | Errors that can happen during the type inference process.
+data InferError =
+    -- | Two types that don't match were attempted to be unified.
+    --
+    -- For example, @a -> a@ and @Int@ do not unify.
+    --
+    -- >>> putPprLn (CannotUnify (TFun "a" "a") (TConst "Int"))
+    -- Cannot unify a → a with Int
+      CannotUnify MType MType
+
+    -- | A 'TVar' is bound to an 'MType' that already contains it.
+    --
+    -- The canonical example of this is @λx. x x@, where the first @x@
+    -- in the body has to have type @a -> b@, and the second one @a@. Since
+    -- they're both the same @x@, this requires unification of @a@ with
+    -- @a -> b@, which only works if @a = a -> b = (a -> b) -> b = …@, yielding
+    -- an infinite type.
+    --
+    -- >>> putPprLn (OccursCheckFailed "a" (TFun "a" "a"))
+    -- Occurs check failed: a already appears in a → a
+    | OccursCheckFailed Name MType
+
+    -- | The value of an unknown identifier was read.
+    --
+    -- >>> putPprLn (UnknownIdentifier "a")
+    -- Unknown identifier: a
+    | UnknownIdentifier Name
+    deriving Show
+
+-- | >>> putPprLn (CannotUnify (TEither "a" "b") (TTuple "a" "b"))
+-- Cannot unify Either a b with (a, b)
+instance Pretty InferError where
+    ppr = \case
+        CannotUnify t1 t2 ->
+            "Cannot unify " <> ppr t1 <> " with " <> ppr t2
+        OccursCheckFailed name ty ->
+            "Occurs check failed: " <> ppr name <> " already appears in " <> ppr ty
+        UnknownIdentifier name ->
+            "Unknown identifier: " <> ppr name
+
+
+
+-- | Evaluate a value in an 'Infer'ence context.
+--
+-- >>> let expr = EAbs "f" (EAbs "g" (EAbs "x" (EApp (EApp "f" "x") (EApp "g" "x"))))
+-- >>> putPprLn expr
+-- λf g x. f x (g x)
+-- >>> let inferred = runInfer (infer (Env []) expr)
+-- >>> let demonstrate = \case Right (_, ty) -> T.putStrLn (":: " <> ppr ty)
+-- >>> demonstrate inferred
+-- :: (c → e → f) → (c → e) → c → f
+runInfer :: Infer a -- ^ Inference data
+         -> Either InferError a
+runInfer (Infer inf) =
+    evalState (runExceptT inf) (map Name (infiniteSupply alphabet))
+  where
+
+    alphabet = map T.singleton ['a'..'z']
+
+    -- [a, b, c] ==> [a,b,c, a1,b1,c1, a2,b2,c2, …]
+    infiniteSupply supply = supply <> addSuffixes supply (1 :: Integer)
+      where
+        addSuffixes xs n = map (\x -> addSuffix x n) xs <> addSuffixes xs (n+1)
+        addSuffix x n = x <> T.pack (show n)
+
+
+
+-- | Throw an 'InferError' in an 'Infer'ence context.
+--
+-- >>> case runInfer (throw (UnknownIdentifier "var")) of Left err -> putPprLn err
+-- Unknown identifier: var
+throw :: InferError -> Infer a
+throw = Infer . throwE
+
+
+
+-- #############################################################################
+-- ** Unification
+-- #############################################################################
+
+-- $ Unification describes the process of making two different types compatible
+-- by specializing them where needed. A desirable property to have here is being
+-- able to find the most general unifier. Luckily, we'll be able to do that in
+-- our type system.
+
+
+
+-- | The unification of two 'MType's is the most general substituion that can be
+-- applied to both of them in order to yield the same result.
+--
+-- >>> let m1 = TFun "a" "b"
+-- >>> putPprLn m1
+-- a → b
+-- >>> let m2 = TFun "c" (TEither "d" "e")
+-- >>> putPprLn m2
+-- c → Either d e
+-- >>> let inferSubst = unify (m1, m2)
+-- >>> case runInfer inferSubst of Right subst -> putPprLn subst
+-- { a ––> c
+-- , b ––> Either d e }
+unify :: (MType, MType) -> Infer Subst
+unify = \case
+    (TFun a b,    TFun x y)          -> unifyBinary (a,b) (x,y)
+    (TVar v,      x)                 -> v `bindVariableTo` x
+    (x,           TVar v)            -> v `bindVariableTo` x
+    (TConst a,    TConst b) | a == b -> pure mempty
+    (TList a,     TList b)           -> unify (a,b)
+    (TEither a b, TEither x y)       -> unifyBinary (a,b) (x,y)
+    (TTuple a b,  TTuple x y)        -> unifyBinary (a,b) (x,y)
+    (a, b)                           -> throw (CannotUnify a b)
+
+  where
+
+    -- Unification of binary type constructors, such as functions and Either.
+    -- Unification is first done for the first operand, and assuming the
+    -- required substitution, for the second one.
+    unifyBinary :: (MType, MType) -> (MType, MType) -> Infer Subst
+    unifyBinary (a,b) (x,y) = do
+        s1 <- unify (a, x)
+        s2 <- unify (applySubst s1 (b, y))
+        pure (s1 <> s2)
+
+
+
+-- | Build a 'Subst'itution that binds a 'Name' of a 'TVar' to an 'MType'. The
+-- resulting substitution should be idempotent, i.e. applying it more than once
+-- to something should not be any different from applying it only once.
+--
+-- - In the simplest case, this just means building a substitution that just
+--   does that.
+-- - Substituting a 'Name' with a 'TVar' with the same name unifies a type
+--   variable with itself, and the resulting substitution does nothing new.
+-- - If the 'Name' we're trying to bind to an 'MType' already occurs in that
+--   'MType', the resulting substitution would not be idempotent: the 'MType'
+--   would be replaced again, yielding a different result. This is known as the
+--   Occurs Check.
+bindVariableTo :: Name -> MType -> Infer Subst
+
+bindVariableTo name (TVar v) | boundToSelf = pure mempty
+  where
+    boundToSelf = name == v
+
+bindVariableTo name mType | name `occursIn` mType = throw (OccursCheckFailed name mType)
+  where
+    n `occursIn` ty = n `S.member` freeMType ty
+
+bindVariableTo name mType = pure (Subst (M.singleton name mType))
+
+
+
+-- #############################################################################
+-- ** Type inference
+-- #############################################################################
+
+-- $ Type inference is the act of finding out a value's type by looking at the
+-- environment it is in, in order to make it compatible with it.
+--
+-- In literature, the Hindley-Damas-Milner inference algorithm ("Algorithm W")
+-- is often presented in the style of logical formulas, and below you'll find
+-- that version along with code that actually does what they say.
+--
+-- These formulas look a bit like fractions, where the "numerator" is a
+-- collection of premises, and the denominator is the consequence if all of them
+-- hold.
+--
+-- __Example:__
+--
+-- @
+-- Γ ⊢ even : Int → Bool   Γ ⊢ 1 : Int
+-- –––––––––––––––––––––––––––––––––––
+--          Γ ⊢ even 1 : Bool
+-- @
+--
+-- means that if we have a value of type @Int -> Bool@ called "even" and a value
+-- of type @Int@ called @1@, then we also have a value of type @Bool@ via
+-- @even 1@ available to us.
+--
+-- The actual inference rules are polymorphic versions of this example, and
+-- the code comments will explain each step in detail.
+
+
+
+-- -----------------------------------------------------------------------------
+-- *** The language: typed lambda calculus
+-- -----------------------------------------------------------------------------
+
+
+
+-- | The syntax tree of the language we'd like to typecheck. You can view it as
+-- a close relative to simply typed lambda calculus, having only the most
+-- necessary syntax elements.
+--
+-- Since 'ELet' is non-recursive, the usual fixed-point function
+-- @fix : (a → a) → a@ can be introduced to allow recursive definitions.
+data Exp = ELit Lit          -- ^ True, 1
+         | EVar Name         -- ^ @x@
+         | EApp Exp Exp      -- ^ @f x@
+         | EAbs Name Exp     -- ^ @λx. e@
+         | ELet Name Exp Exp -- ^ @let x = e in e'@ (non-recursive)
+         deriving Show
+
+
+
+-- | Literals we'd like to support. Since we can't define new data types in our
+-- simple type system, we'll have to hard-code the possible ones here.
+data Lit = LBool Bool
+         | LInteger Integer
+         deriving Show
+
+
+
+-- | >>> putPprLn (EAbs "f" (EAbs "g" (EAbs "x" (EApp (EApp "f" "x") (EApp "g" "x")))))
+-- λf g x. f x (g x)
+instance Pretty Exp where
+    ppr (ELit lit) = ppr lit
+
+    ppr (EVar name) = ppr name
+
+    ppr (EApp f x) = pprApp1 f <> " " <> pprApp2 x
+      where
+        pprApp1 = \case
+            eLet@ELet{} -> "(" <> ppr eLet <> ")"
+            eLet@EAbs{} -> "(" <> ppr eLet <> ")"
+            e -> ppr e
+        pprApp2 = \case
+            eApp@EApp{} -> "(" <> ppr eApp <> ")"
+            e -> pprApp1 e
+
+    ppr x@EAbs{} = pprAbs True x
+      where
+        pprAbs True  (EAbs name expr) = "λ" <> ppr name <> pprAbs False expr
+        pprAbs False (EAbs name expr) = " " <> ppr name <> pprAbs False expr
+        pprAbs _ expr                 = ". " <> ppr expr
+
+    ppr (ELet name value body) =
+        "let " <> ppr name <> " = " <> ppr value <> " in " <> ppr body
+
+-- | >>> putPprLn (LBool True)
+-- True
+--
+-- >>> putPprLn (LInteger 127)
+-- 127
+instance Pretty Lit where
+    ppr = \case
+        LBool    b -> showT b
+        LInteger i -> showT i
+      where
+        showT :: Show a => a -> Text
+        showT = T.pack . show
+
+-- | >>> "var" :: Exp
+-- EVar (Name "var")
+instance IsString Exp where
+    fromString = EVar . fromString
+
+
+
+-- -----------------------------------------------------------------------------
+-- *** Some useful definitions
+-- -----------------------------------------------------------------------------
+
+
+
+-- | Generate a fresh 'Name' in a type 'Infer'ence context. An example use case
+-- of this is η expansion, which transforms @f@ into @λx. f x@, where "x" is a
+-- new name, i.e. unbound in the current context.
+fresh :: Infer MType
+fresh = drawFromSupply >>= \case
+    Right name -> pure (TVar name)
+    Left err -> throw err
+
+  where
+
+    drawFromSupply :: Infer (Either InferError Name)
+    drawFromSupply = Infer (do
+        s:upply <- lift get
+        lift (put upply)
+        pure (Right s) )
+
+
+
+-- | Add a new binding to the environment.
+--
+-- The Haskell equivalent would be defining a new value, for example in module
+-- scope or in a @let@ block. This corresponds to the "comma" operation used in
+-- formal notation,
+--
+-- @
+-- Γ, x:σ  ≡  extendEnv Γ (x,σ)
+-- @
+extendEnv :: Env -> (Name, PType) -> Env
+extendEnv (Env env) (name, pType) = Env (M.insert name pType env)
+
+
+
+-- -----------------------------------------------------------------------------
+-- *** Inferring the types of all language constructs
+-- -----------------------------------------------------------------------------
+
+
+
+-- | Infer the type of an 'Exp'ression in an 'Env'ironment, resulting in the
+-- 'Exp's 'MType' along with a substitution that has to be done in order to reach
+-- this goal.
+--
+-- This is widely known as /Algorithm W/.
+infer :: Env -> Exp -> Infer (Subst, MType)
+infer env = \case
+    ELit lit    -> inferLit lit
+    EVar name   -> inferVar env name
+    EApp f x    -> inferApp env f x
+    EAbs x e    -> inferAbs env x e
+    ELet x e e' -> inferLet env x e e'
+
+
+
+-- | Literals such as 'True' and '1' have their types hard-coded.
+inferLit :: Lit -> Infer (Subst, MType)
+inferLit lit = pure (mempty, TConst litTy)
+  where
+    litTy = case lit of
+        LBool    {} -> "Bool"
+        LInteger {} -> "Integer"
+
+
+
+-- | Inferring the type of a variable is done via
+--
+-- @
+-- x:σ ∈ Γ   τ = instantiate(σ)
+-- ––––––––––––––––––––––––––––  [Var]
+--            Γ ⊢ x:τ
+-- @
+--
+-- This means that if @Γ@ /literally contains/ (@∈@) a value, then it also
+-- /entails it/ (@⊢@) in all its instantiations.
+inferVar :: Env -> Name -> Infer (Subst, MType)
+inferVar env name = do
+    sigma <- lookupEnv env name -- x:σ ∈ Γ
+    tau <- instantiate sigma    -- τ = instantiate(σ)
+                                -- ------------------
+    pure (mempty, tau)          -- Γ ⊢ x:τ
+
+
+
+-- | Look up the 'PType' of a 'Name' in the 'Env'ironment.
+--
+-- This checks whether @x:σ@ is /literally contained/ in @Γ@. For more details
+-- about this, see the documentation of 'Env'.
+--
+-- To give a Haskell analogon, looking up @id@ when @Prelude@ is loaded, the
+-- resulting 'PType' would be @id@'s type, namely @forall a. a -> a@.
+lookupEnv :: Env -> Name -> Infer PType
+lookupEnv (Env env) name = case M.lookup name env of
+    Just x  -> pure x
+    Nothing -> throw (UnknownIdentifier name)
+
+
+
+-- | Bind all quantified variables of a 'PType' to 'fresh' type variables.
+--
+-- __Example:__ instantiating @forall a. a -> b -> a@ results in the 'MType'
+-- @c -> b -> c@, where @c@ is a fresh name (to avoid shadowing issues).
+--
+-- You can picture the 'PType' to be the prototype converted to an instantiated
+-- 'MType', which can now be used in the unification process.
+--
+-- Another way of looking at it is by simply forgetting which variables were
+-- quantified, carefully avoiding name clashes when doing so.
+--
+-- 'instantiate' can also be seen as the opposite of 'generalize', which we'll
+-- need later to convert an 'MType' to a 'PType'.
+instantiate :: PType -> Infer MType
+instantiate (Forall qs t) = do
+    subst <- substituteAllWithFresh qs
+    pure (applySubst subst t)
+
+  where
+    -- For each given name, add a substitution from that name to a fresh type
+    -- variable to the result.
+    substituteAllWithFresh :: Set Name -> Infer Subst
+    substituteAllWithFresh xs = do
+        let freshSubstActions = M.fromSet (const fresh) xs
+        freshSubsts <- sequenceA freshSubstActions
+        pure (Subst freshSubsts)
+
+
+
+-- | Function application captures the fact that if we have a function and an
+-- argument we can give to that function, we also have the result value of the
+-- result type available to us.
+--
+-- @
+-- Γ ⊢ f : fτ   Γ ⊢ x : xτ   fxτ = fresh   unify(fτ, xτ → fxτ)
+-- –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––  [App]
+--                       Γ ⊢ f x : fxτ
+-- @
+--
+-- This rule says that given a function and a value with a type, the function
+-- type has to unify with a function type that allows the value type to be its
+-- argument.
+inferApp
+    :: Env
+    -> Exp -- ^ __f__ x
+    -> Exp -- ^ f __x__
+    -> Infer (Subst, MType)
+inferApp env f x = do
+    (s1, fTau) <- infer env f                         -- f : fτ
+    (s2, xTau) <- infer (applySubst s1 env) x         -- x : xτ
+    fxTau <- fresh                                    -- fxτ = fresh
+    s3 <- unify (applySubst s2 fTau, TFun xTau fxTau) -- unify (fτ, xτ → fxτ)
+    let s = s3 <> s2 <> s1                            -- --------------------
+    pure (s, applySubst s3 fxTau)                     -- f x : fxτ
+
+
+
+-- | Lambda abstraction is based on the fact that when we introduce a new
+-- variable, the resulting lambda maps from that variable's type to the type of
+-- the body.
+--
+-- @
+-- τ = fresh   σ = ∀∅. τ   Γ, x:σ ⊢ e:τ'
+-- –––––––––––––––––––––––––––––––––––––  [Abs]
+--             Γ ⊢ λx.e : τ→τ'
+-- @
+--
+-- Here, @Γ, x:τ@ is @Γ@ extended by one additional mapping, namely @x:τ@.
+--
+-- Abstraction is typed by extending the environment by a new 'MType', and if
+-- under this assumption we can construct a function mapping to a value of that
+-- type, we can say that the lambda takes a value and maps to it.
+inferAbs
+    :: Env
+    -> Name -- ^ λ__x__. e
+    -> Exp  -- ^ λx. __e__
+    -> Infer (Subst, MType)
+inferAbs env x e = do
+    tau <- fresh                           -- τ = fresh
+    let sigma = Forall [] tau              -- σ = ∀∅. τ
+        env' = extendEnv env (x, sigma)    -- Γ, x:σ …
+    (s, tau') <- infer env' e              --        … ⊢ e:τ'
+                                           -- ---------------
+    pure (s, TFun (applySubst s tau) tau') -- λx.e : τ→τ'
+
+
+
+-- | A let binding allows extending the environment with new bindings in a
+-- principled manner. To do this, we first have to typecheck the expression to
+-- be introduced. The result of this is then generalized to a 'PType', since let
+-- bindings introduce new polymorphic values, which are then added to the
+-- environment. Now we can finally typecheck the body of the "in" part of the
+-- let binding.
+--
+-- Note that in our simple language, let is non-recursive, but recursion can be
+-- introduced as usual by adding a primitive @fix : (a → a) → a@ if desired.
+--
+-- @
+-- Γ ⊢ e:τ   σ = gen(Γ,τ)   Γ, x:σ ⊢ e':τ'
+-- –––––––––––––––––––––––––––––––––––––––  [Let]
+--         Γ ⊢ let x = e in e' : τ'
+-- @
+inferLet
+    :: Env
+    -> Name -- ^ let __x__ = e in e'
+    -> Exp -- ^ let x = __e__ in e'
+    -> Exp -- ^ let x = e in __e'__
+    -> Infer (Subst, MType)
+inferLet env x e e' = do
+    (s1, tau) <- infer env e              -- Γ ⊢ e:τ
+    let env' = applySubst s1 env
+    let sigma = generalize env' tau       -- σ = gen(Γ,τ)
+    let env'' = extendEnv env' (x, sigma) -- Γ, x:σ
+    (s2, tau') <- infer env'' e'          -- Γ ⊢ …
+                                          -- --------------------------
+    pure (s2 <> s1, tau')                 --     … let x = e in e' : τ'
+
+
+
+-- | Generalize an 'MType' to a 'PType' by universally quantifying over all the
+-- type variables contained in it, except those already free in the environment.
+--
+-- >>> let tau = TFun "a" (TFun "b" "a")
+-- >>> putPprLn tau
+-- a → b → a
+-- >>> putPprLn (generalize (Env [("x", Forall [] "b")]) tau)
+-- ∀a. a → b → a
+--
+-- In more formal notation,
+--
+-- @
+-- gen(Γ,τ) = ∀{α}. τ
+--     where {α} = free(τ) – free(Γ)
+-- @
+--
+-- 'generalize' can also be seen as the opposite of 'instantiate', which
+-- converts a 'PType' to an 'MType'.
+generalize :: Env -> MType -> PType
+generalize env mType = Forall qs mType
+  where
+    qs = freeMType mType `S.difference` freeEnv env

Main.hs

@@ -0,0 +1,185 @@
+{-# LANGUAGE OverloadedLists   #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+module Main where
+
+
+
+import qualified Data.Map     as M
+import           Data.Monoid
+import           Data.Text    (Text)
+import qualified Data.Text.IO as T
+
+import HindleyMilner
+
+
+
+-- #############################################################################
+-- #############################################################################
+-- * Testing
+-- #############################################################################
+-- #############################################################################
+
+
+
+-- #############################################################################
+-- ** A small custom Prelude
+-- #############################################################################
+
+
+
+prelude :: Env
+prelude = Env (M.fromList
+    [ ("(*)",        Forall []              (tInteger ~> tInteger ~> tInteger))
+    , ("(+)",        Forall []              (tInteger ~> tInteger ~> tInteger))
+    , ("(,)",        Forall ["a","b"]       ("a" ~> "b" ~> TTuple "a" "b"))
+    , ("(-)",        Forall []              (tInteger ~> tInteger ~> tInteger))
+    , ("(.)",        Forall ["a", "b", "c"] (("b" ~> "c") ~> ("a" ~> "b") ~> "a" ~> "c"))
+    , ("(<)",        Forall []              (tInteger ~> tInteger ~> tBool))
+    , ("(<=)",       Forall []              (tInteger ~> tInteger ~> tBool))
+    , ("(>)",        Forall []              (tInteger ~> tInteger ~> tBool))
+    , ("(>=)",       Forall []              (tInteger ~> tInteger ~> tBool))
+    , ("const",      Forall ["a","b"]       ("a" ~> "b" ~> "a"))
+    , ("Cont/>>=",   Forall ["a"]           ((("a" ~> "r") ~> "r") ~> ("a" ~> (("b" ~> "r") ~> "r")) ~> (("b" ~> "r") ~> "r")))
+    , ("find",       Forall ["a","b"]       (("a" ~> tBool) ~> TList "a" ~> tMaybe "a"))
+    , ("fix",        Forall ["a"]           (("a" ~> "a") ~> "a"))
+    , ("foldr",      Forall ["a","b"]       (("a" ~> "b" ~> "b") ~> "b" ~> TList "a" ~> "b"))
+    , ("id",         Forall ["a"]           ("a" ~> "a"))
+    , ("ifThenElse", Forall ["a"]           (tBool ~> "a" ~> "a" ~> "a"))
+    , ("Left",       Forall ["a","b"]       ("a" ~> TEither "a" "b"))
+    , ("length",     Forall ["a"]           (TList "a" ~> tInteger))
+    , ("map",        Forall ["a","b"]       (("a" ~> "b") ~> TList "a" ~> TList "b"))
+    , ("reverse",    Forall ["a"]           (TList "a" ~> TList "a"))
+    , ("Right",      Forall ["a","b"]       ("b" ~> TEither "a" "b"))
+    , ("[]",         Forall ["a"]           (TList "a"))
+    , ("(:)",        Forall ["a"]           ("a" ~> TList "a" ~> TList "a"))
+    ])
+  where
+    tBool = TConst "Bool"
+    tInteger = TConst "Integer"
+    tMaybe = TEither (TConst "()")
+
+
+
+-- | Synonym for 'TFun' to make writing type signatures easier.
+--
+-- Instead of
+--
+-- @
+-- Forall ["a","b"] (TFun "a" (TFun "b" "a"))
+-- @
+--
+-- we can write
+--
+-- @
+-- Forall ["a","b"] ("a" ~> "b" ~> "a")
+-- @
+(~>) :: MType -> MType -> MType
+(~>) = TFun
+infixr 9 ~>
+
+
+
+-- #############################################################################
+-- ** Run it!
+-- #############################################################################
+
+
+
+-- | Run type inference on a cuple of values
+main :: IO ()
+main = do
+    let inferAndPrint = T.putStrLn . ("  " <>) . showType prelude
+    T.putStrLn "Well-typed:"
+    do
+        inferAndPrint (lambda ["x"] "x")
+        inferAndPrint (lambda ["f","g","x"] (apply "f" ["x", apply "g" ["x"]]))
+        inferAndPrint (lambda ["f","g","x"] (apply "f" [apply "g" ["x"]]))
+        inferAndPrint (lambda ["m", "k", "c"] (apply "m" [lambda ["x"] (apply "k" ["x", "c"])])) -- >>= for Cont
+        inferAndPrint (lambda ["f"] (apply "(.)" ["reverse", apply "map" ["f"]]))
+        inferAndPrint (apply "find" [lambda ["x"] (apply "(>)" ["x", int 0])])
+        inferAndPrint (apply "map" [apply "map" ["map"]])
+        inferAndPrint (apply "(*)" [int 1, int 2])
+        inferAndPrint (apply "foldr" ["(+)", int 0])
+        inferAndPrint (apply "map" ["length"])
+        inferAndPrint (apply "map" ["map"])
+        inferAndPrint (lambda ["x"] (apply "ifThenElse" [apply "(<)" ["x", int 0], int 0, "x"]))
+        inferAndPrint (lambda ["x"] (apply "fix" [lambda ["xs"] (apply "(:)" ["x", "xs"])]))
+    T.putStrLn "Ill-typed:"
+    do
+        inferAndPrint (apply "(*)" [int 1, bool True])
+        inferAndPrint (apply "foldr" [int 1])
+        inferAndPrint (lambda ["x"] (apply "x" ["x"]))
+        inferAndPrint (lambda ["x"] (ELet "xs" (apply "(:)" ["x", "xs"]) "xs"))
+
+
+
+-- | Build multiple lambda bindings.
+--
+-- Instead of
+--
+-- @
+-- EAbs "f" (EAbs "x" (EApp "f" "x"))
+-- @
+--
+-- we can write
+--
+-- @
+-- lambda ["f", "x"] (EApp "f" "x")
+-- @
+--
+-- for
+--
+-- @
+-- λf x. f x
+-- @
+lambda :: [Name] -> Exp -> Exp
+lambda names expr = foldr EAbs expr names
+
+
+
+-- | Apply a function to multiple arguments.
+--
+-- Instead of
+--
+-- @
+-- EApp (EApp (EApp "f" "x") "y") "z")
+-- @
+--
+-- we can write
+--
+-- @
+-- apply "f" ["x", "y", "z"]
+-- @
+--
+-- for
+--
+-- @
+-- f x y z
+-- @
+apply :: Exp -> [Exp] -> Exp
+apply = foldl EApp
+
+
+
+-- | Construct an integer literal.
+int :: Integer -> Exp
+int = ELit . LInteger
+
+
+
+-- | Construct a boolean literal.
+bool :: Bool -> Exp
+bool = ELit . LBool
+
+
+
+-- | Convenience function to run type inference algorithm
+showType :: Env    -- ^ Starting environment, e.g. 'prelude'.
+         -> Exp    -- ^ Expression to typecheck
+         -> Text   -- ^ Text representation of the result. Contains an error
+                   --   message on failure.
+showType env expr =
+    case (runInfer . fmap (generalize (Env mempty) . uncurry applySubst) . infer env) expr of
+        Left err -> "Error inferring type of " <> ppr expr <>": " <> ppr err
+        Right ty -> ppr expr <> " :: " <> ppr ty

README.md

@@ -1,18 +1,22 @@
 
-TODO:
--null-only language should be called Maaru
--haskell-ish langauge should be called Robo
--typeful scripting language should be called schala
-rename accordingly!
-
 # Schala - a programming language meta-interpreter
 
-Schala is a Rust-language framework written to make it easy to
+Schala is a Rust framework written to make it easy to
 create and experiment with toy programming languages. It provides
-a common REPL, and a trait `ProgrammingLanguage` with methods
+a common REPL, and a trait `ProgrammingLanguage` with provisions
 for tokenizing text, parsing tokens, evaluating an abstract syntax tree,
 and other tasks that are common to all programming languages.
 
+Schala is implemented as a Rust library `schala_lib`, which provides a
+`schala_main` function. This function serves as the main loop of the REPL, if run
+interactively, or otherwise reads and interprets programming language source
+files. It expects as input a vector of `PLIGenerator`, which is a type representing
+a closure that returns a boxed trait object that implements the `ProgrammingLanguage` trait,
+and stores any persistent state relevant to that programming language. The ability
+to share state between different programming languages is in the works.
+
+## About
+
 Schala started out life as an experiment in writing a Javascript-like
 programming language that would never encounter any kind of runtime value
 error, but rather always return `null` under any kind of error condition. I had
@@ -29,6 +33,8 @@ creating a language name confusingly close to Scala. The naming scheme for
 languages implemented with the Schala meta-interpreter is Chrono Trigger
 characters.
 
+Schala is incomplete alpha software and is not ready for public release.
+
 ## Languages implemented using the meta-interpreter
 
 * The eponymous *Schala* language is an interpreted/compiled scripting langauge,
@@ -43,6 +49,8 @@ system.
 * *Robo* is an experiment in creating a lazy, functional, strongly-typed language
 much like Haskell
 
+* *Rukka* is a straightforward LISP implementation
+
 ## Reference works
 
 Here's a partial list of resources I've made use of in the process
@@ -50,6 +58,8 @@ of learning how to write a programming language.
 
 ### 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
 
 ### Evaluation
 *Understanding Computation*, Tom Stuart, O'Reilly 2013
@@ -58,6 +68,7 @@ https://skillsmatter.com/skillscasts/10868-inside-the-rust-compiler
 
 ### 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/)
 

TODO.md

@@ -0,0 +1,126 @@
+
+# TODO Items
+
+-make sure to include a :doc command at the REPL that can interface with a lang in a generic way
+
+- a subtype is a situation where the compiler is entitled to add a type conversion in the type-checking process
+b/c that type conversion doesn't correspond to a computation 
+    -Sergei W.
+
+*A neat idea for pattern matching optimization would be if you could match on one of several things in a list
+ex:
+if x {
+ is (comp, LHSPat, RHSPat) if comp in ["==, "<"] -> ...
+}
+
+
+- https://nshipster.com/never/
+-https://cranelift.readthedocs.io/en/latest/?badge=latest<Paste>
+
+-consult http://gluon-lang.org/book/embedding-api.html
+
+- if/match playground
+
+simple if
+`if x == 1.0 { "a" } else { "b" }`
+
+one comparison multiple targets:
+`if x == { 1.0 -> "a", 2.0 -> "b", else -> "c" }`
+
+different comparison operators/ method calls:
+`if x { == 1.0 -> "a", eq NaN -> "n", .hella() -> "h", else -> "z" }`
+
+pattern matching/introducing bindings:
+`if alice { .age < 18 -> "18", is Person("Alice", age) -> "${age}", else -> "none" }`
+
+pattern matching w/ if-let:
+`if person is Person("Alice", age) { "${age}" } else { "nope" }`
+
+-https://soc.github.io/languages/unified-condition-syntax syntax:
+
+`if <cond-expr>" then <then-expr> else <else-expr>`
+`if <half-expr> \n <rest-expr1> then <result1-expr> \n <rest-expr2> then <result-expr2> else <result3-expr>`
+-and rest-exprs (or "targets") can have 'is' for pattern-matching, actually so can a full cond-expr
+
+UNIFIED IF EXPRESSIONS FINAL WORK:
+
+basic syntax:
+
+`if_expr := if discriminator '{' (guard_expr)* '}'`
+`guard_expr := pattern 'then' block_or_expr'`
+`pattern := rhs | is_pattern`
+`is_pattern := 'is' ???`
+`rhs := expression | ???`
+
+
+if the only two guard patterns are true and false, then the abbreviated syntax:
+`'if' discriminator 'then' block_or_expr 'else' block_or_expr`
+can replace `'if' discriminator '{' 'true' 'then' block_or_expr; 'false' 'then' block_or_expr '}'`
+
+
+
+
+- Next priorities: - get ADTs working, get matches working
+
+- inclusive/exclusive range syntax like .. vs ..=
+
+- sketch of an idea for the REPL:
+        -each compiler pass should be a (procedural?) macro like
+        compiler_pass!("parse", dataproducts: ["ast", "parse_tree"], {
+         match parsing::parse(INPUT) {
+           Ok(
+                PASS.add_artifact(
+        }
+
+-should have an Idris-like `cast To From` function
+
+- REPL:
+  - want to be able to do things like `:doc Identifier`, and have the language load up these definitions to the REPL
+
+
+* change 'trait' to 'interface'
+  -think about idris-related ideas of multiple implementations of a type for an interface (+ vs * impl for monoids, for preorder/inorder/postorder for Foldable)
+
+* Share state between programming languages
+
+* idea for Schala - scoped types - be able to define a quick enum type scoped to a function ro something, that only is meant to be used as a quick bespoke interface between two other things
+
+* another idea, allow:
+type enum {
+  type enum MySubVariant {
+    SubVariant1, SubVariant2, etc.
+    }
+ Variant1(MySubVariant),
+ Variant2(...),
+ }
+
+
+
+* idea for Schala: both currying *and* default arguments!
+        ex. 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
+            a(1,2, c=_): Int -> Int
+            a(_,_,_) : Int -> Int -> Int -> Int
+
+
+
+- AST : maybe replace the Expression type with "Ascription(TypeName, Box<Expression>) nodes??
+- parser: add a "debug" field to the Parser struct for all debug-related things
+
+-scala-style html"dfasfsadf${}" string interpolations!
+
+*Compiler passes architecture
+
+-ProgrammingLanguageInterface defines a evaluate_in_repl() and evaluate_no_repl() functions
+-these take in a vec of CompilerPasses
+
+struct CompilerPass {
+        name: String,
+        run: fn(PrevPass) -> NextPass
+}
+
+-change "Type...." names in parser.rs to "Anno..." for non-collision with names in typechecking.rs
+
+-get rid of code pertaining to compilation specifically, have a more generation notion of "execution type"

maaru/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "maaru-lang"
+version = "0.1.0"
+authors = ["greg <greg.shuflin@protonmail.com>"]
+
+[dependencies]
+itertools = "0.5.8"
+take_mut = "0.1.3"
+llvm-sys = "*"
+
+schala-repl = { path = "../schala-repl" }

maaru/src/compilation.rs

@@ -5,10 +5,10 @@ use std::collections::HashMap;
 use self::llvm_sys::prelude::*;
 use self::llvm_sys::{LLVMIntPredicate};
 
-use maaru_lang::parser::{AST, Statement, Function, Prototype, Expression, BinOp};
-use language::LLVMCodeString;
+use parser::{AST, Statement, Function, Prototype, Expression, BinOp};
+use schala_repl::LLVMCodeString;
 
-use llvm_wrap as LLVMWrap;
+use schala_repl::llvm_wrap as LLVMWrap;
 
 type VariableMap = HashMap<String, LLVMValueRef>;
 

maaru/src/eval.rs

@@ -2,13 +2,13 @@ extern crate take_mut;
 
 use std::collections::HashMap;
 use std::collections::VecDeque;
-use maaru_lang::parser::{AST, Statement, Expression, Function, Callable, BinOp};
+use parser::{AST, Statement, Expression, Function, Callable, BinOp};
 use std::rc::Rc;
 use std::io::{Write, Stdout, BufWriter};
 use std::convert::From;
 
-use maaru_lang::parser::Expression::*;
-use maaru_lang::parser::Statement::*;
+use parser::Expression::*;
+use parser::Statement::*;
 
 type Reduction<T> = (T, Option<SideEffect>);
 

maaru/src/lib.rs

@@ -1,9 +1,24 @@
-pub mod tokenizer;
-pub mod parser;
-pub mod eval;
-pub mod compilation;
+#![feature(box_patterns)]
 
-use language::{ProgrammingLanguageInterface, EvalOptions, ReplOutput, TraceArtifact, LLVMCodeString};
+extern crate schala_repl;
+
+mod tokenizer;
+mod parser;
+mod eval;
+mod compilation;
+
+use schala_repl::{ProgrammingLanguageInterface, EvalOptions, UnfinishedComputation, FinishedComputation, TraceArtifact};
+
+#[derive(Debug)]
+pub struct TokenError {
+    pub msg: String,
+}
+
+impl TokenError {
+    pub fn new(msg: &str) -> TokenError {
+        TokenError { msg: msg.to_string() }
+    }
+}
 
 pub use self::eval::Evaluator as MaaruEvaluator;
 
@@ -27,42 +42,41 @@ impl<'a> ProgrammingLanguageInterface for Maaru<'a> {
     format!("maaru")
   }
 
-  fn evaluate_in_repl(&mut self, input: &str, options: &EvalOptions) -> ReplOutput {
-    let mut output = ReplOutput::default();
+  fn execute_pipeline(&mut self, input: &str, options: &EvalOptions) -> FinishedComputation {
+    let mut output = UnfinishedComputation::default();
 
     let tokens = match tokenizer::tokenize(input) {
       Ok(tokens) => {
-        if options.debug_tokens {
+        if let Some(_) = options.debug_passes.get("tokens") {
           output.add_artifact(TraceArtifact::new("tokens", format!("{:?}", tokens)));
         }
         tokens
       },
       Err(err) => {
-        output.add_output(format!("Tokenization error: {:?}\n", err.msg));
-        return output;
+        return output.finish(Err(format!("Tokenization error: {:?}\n", err.msg)))
       }
     };
 
     let ast = match parser::parse(&tokens, &[]) {
       Ok(ast) => {
-        if options.debug_parse {
+        if let Some(_) = options.debug_passes.get("ast") {
           output.add_artifact(TraceArtifact::new("ast", format!("{:?}", ast)));
         }
         ast
       },
       Err(err) => {
-        output.add_output(format!("Parse error: {:?}\n", err.msg));
-        return output;
+        return output.finish(Err(format!("Parse error: {:?}\n", err.msg)))
       }
     };
     let mut evaluation_output = String::new();
     for s in self.evaluator.run(ast).iter() {
       evaluation_output.push_str(s);
     }
-    output.add_output(evaluation_output);
-    return output;
+    output.finish(Ok(evaluation_output))
   }
 
+  /* TODO make this work with new framework */
+  /*
   fn can_compile(&self) -> bool {
     true
   }
@@ -85,4 +99,5 @@ impl<'a> ProgrammingLanguageInterface for Maaru<'a> {
     };
     compilation::compile_ast(ast)
   }
+  */
 }

maaru/src/parser.rs

@@ -1,5 +1,5 @@
-use maaru_lang::tokenizer::{Token, Kw, OpTok};
-use maaru_lang::tokenizer::Token::*;
+use tokenizer::{Token, Kw, OpTok};
+use tokenizer::Token::*;
 
 use std::fmt;
 use std::collections::VecDeque;

maaru/src/tokenizer.rs

@@ -5,7 +5,7 @@ use std::str::Chars;
 use self::itertools::Itertools;
 use std::rc::Rc;
 
-use language::TokenError;
+use TokenError;
 
 #[derive(Debug, Clone, PartialEq)]
 pub enum Token {

robo/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "robo-lang"
+version = "0.1.0"
+authors = ["greg <greg.shuflin@protonmail.com>"]
+
+[dependencies]
+itertools = "0.5.8"
+take_mut = "0.1.3"
+llvm-sys = "*"
+
+schala-repl = { path = "../schala-repl" }

robo/src/lib.rs

@@ -1,6 +1,10 @@
-use itertools::Itertools;
+#![feature(box_patterns)]
 
-use language::{ProgrammingLanguageInterface, EvalOptions, ReplOutput, TokenError};
+extern crate itertools;
+extern crate schala_repl;
+
+use itertools::Itertools;
+use schala_repl::{ProgrammingLanguageInterface, EvalOptions, FinishedComputation, UnfinishedComputation};
 
 pub struct Robo {
 }
@@ -11,6 +15,17 @@ impl Robo {
   }
 }
 
+#[derive(Debug)]
+pub struct TokenError {
+    pub msg: String,
+}
+
+impl TokenError {
+    pub fn new(msg: &str) -> TokenError {
+        TokenError { msg: msg.to_string() }
+    }
+}
+
 #[allow(dead_code)]
 #[derive(Debug)]
 pub enum Token {
@@ -140,18 +155,16 @@ impl ProgrammingLanguageInterface for Robo {
     format!("robo")
   }
 
-  fn evaluate_in_repl(&mut self, input: &str, _eval_options: &EvalOptions) -> ReplOutput {
-    let mut output = ReplOutput::default();
+  fn execute_pipeline(&mut self, input: &str, _eval_options: &EvalOptions) -> FinishedComputation {
+    let output = UnfinishedComputation::default();
     let tokens = match tokenize(input) {
       Ok(tokens) => tokens,
       Err(e) => {
-        output.add_output(format!("Tokenize error: {:?}", e));
-        return output;
+        return output.finish(Err(format!("Tokenize error: {:?}", e)));
       }
     };
 
-    output.add_output(format!("{:?}", tokens));
-    output
+    output.finish(Ok(format!("{:?}", tokens)))
   }
 }
 

rukka/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "rukka-lang"
+version = "0.1.0"
+authors = ["greg <greg.shuflin@protonmail.com>"]
+
+[dependencies]
+itertools = "0.5.8"
+take_mut = "0.1.3"
+llvm-sys = "*"
+
+schala-repl = { path = "../schala-repl" }

rukka/src/lib.rs

@@ -0,0 +1,435 @@
+#![feature(box_patterns)]
+
+extern crate itertools;
+extern crate schala_repl;
+
+use itertools::Itertools;
+use schala_repl::{ProgrammingLanguageInterface, EvalOptions, UnfinishedComputation, FinishedComputation};
+use std::iter::Peekable;
+use std::vec::IntoIter;
+use std::str::Chars;
+use std::collections::HashMap;
+
+pub struct EvaluatorState {
+  binding_stack: Vec<HashMap<String, Sexp>>
+}
+
+impl EvaluatorState {
+  fn new() -> EvaluatorState {
+    use self::Sexp::Primitive;
+    use self::PrimitiveFn::*;
+    let mut default_map = HashMap::new();
+    default_map.insert(format!("+"), Primitive(Plus));
+    default_map.insert(format!("-"), Primitive(Minus));
+    default_map.insert(format!("*"), Primitive(Mult));
+    default_map.insert(format!("/"), Primitive(Div));
+    default_map.insert(format!("%"), Primitive(Mod));
+    default_map.insert(format!(">"), Primitive(Greater));
+    default_map.insert(format!("<"), Primitive(Less));
+    default_map.insert(format!("<="), Primitive(LessThanOrEqual));
+    default_map.insert(format!(">="), Primitive(GreaterThanOrEqual));
+    default_map.insert(format!("display"), Primitive(Display));
+
+    EvaluatorState {
+      binding_stack: vec![default_map],
+    }
+  }
+  fn set_var(&mut self, var: String, value: Sexp) {
+    let binding = self.binding_stack.last_mut().unwrap();
+    binding.insert(var, value);
+  }
+  fn get_var(&self, var: &str) -> Option<&Sexp> {
+    for bindings in self.binding_stack.iter().rev() {
+      match bindings.get(var) {
+        Some(x)  => return Some(x),
+        None => (),
+      }
+    }
+    None
+  }
+
+  fn push_env(&mut self) {
+    self.binding_stack.push(HashMap::new());
+  }
+  fn pop_env(&mut self) {
+    self.binding_stack.pop();
+  }
+}
+
+pub struct Rukka {
+  state: EvaluatorState
+}
+
+impl Rukka {
+  pub fn new() -> Rukka { Rukka { state: EvaluatorState::new() } }
+}
+
+impl ProgrammingLanguageInterface for Rukka {
+  fn get_language_name(&self) -> String {
+    "Rukka".to_string()
+  }
+
+  fn get_source_file_suffix(&self) -> String {
+    format!("rukka")
+  }
+
+  fn execute_pipeline(&mut self, input: &str, _eval_options: &EvalOptions) -> FinishedComputation {
+    let output = UnfinishedComputation::default();
+    let sexps = match read(input) {
+      Err(err) => {
+        return output.finish(Err(format!("Error: {}", err)));
+      },
+      Ok(sexps) => sexps
+    };
+
+    let output_str: String = sexps.into_iter().enumerate().map(|(i, sexp)| {
+      match self.state.eval(sexp) {
+        Ok(result) => format!("{}: {}", i, result.print()),
+        Err(err) => format!("{} Error: {}", i, err),
+      }
+    }).intersperse(format!("\n")).collect();
+    output.finish(Ok(output_str))
+  }
+}
+
+impl EvaluatorState {
+  fn eval(&mut self, expr: Sexp) -> Result<Sexp, String> {
+    use self::Sexp::*;
+    Ok(match expr {
+      SymbolAtom(ref sym) => match self.get_var(sym) {
+        Some(ref sexp) => {
+          let q: &Sexp = sexp; //WTF? if I delete this line, the copy doesn't work??
+          q.clone() //TODO make this not involve a clone
+        },
+        None => return Err(format!("Variable {} not bound", sym)),
+      },
+      expr @ Primitive(_) => expr,
+      expr @ FnLiteral { .. } => expr,
+      expr @ StringAtom(_) => expr,
+      expr @ NumberAtom(_) => expr,
+      expr @ BoolAtom(_) => expr,
+      Cons(box operator, box operands) => match operator {
+        SymbolAtom(ref sym) if match &sym[..] {
+          "quote" | "eq?" | "cons" | "car" | "cdr" | "atom?" | "define" | "lambda" | "if" | "cond" => true, _ => false
+          } => self.eval_special_form(sym, operands)?,
+        _ => {
+          let evaled = self.eval(operator)?;
+          self.apply(evaled, operands)?
+        }
+      },
+      Nil => Nil,
+    })
+  }
+  fn eval_special_form(&mut self, form: &str, operands: Sexp) -> Result<Sexp, String> {
+    use self::Sexp::*;
+    Ok(match form {
+      "quote" => match operands {
+        Cons(box quoted, box Nil) => quoted,
+        _ => return Err(format!("Bad syntax in quote")),
+      },
+      "eq?" => match operands {//TODO make correct
+        Cons(box lhs, box Cons(box rhs, _)) => BoolAtom(lhs == rhs),
+        _ => BoolAtom(true),
+      },
+      "cons" => match operands {
+        Cons(box cadr, box Cons(box caddr, box Nil)) => {
+          let newl = self.eval(cadr)?;
+          let newr = self.eval(caddr)?;
+          Cons(Box::new(newl), Box::new(newr))
+        },
+        _ => return Err(format!("Bad arguments for cons")),
+      },
+      "car" => match operands {
+        Cons(box car, _) => car,
+        _ => return Err(format!("called car with a non-pair argument")),
+      },
+      "cdr" => match operands {
+        Cons(_, box cdr) => cdr,
+        _ => return Err(format!("called cdr with a non-pair argument")),
+      },
+      "atom?" => match operands {
+        Cons(_, _) => BoolAtom(false),
+        _ => BoolAtom(true),
+      },
+      "define" => match operands {
+        Cons(box SymbolAtom(sym), box Cons(box expr, box Nil)) => {
+          let evaluated = self.eval(expr)?;
+          self.set_var(sym, evaluated);
+          Nil
+        },
+        _ => return Err(format!("Bad assignment")),
+      }
+      "lambda" => match operands {
+        Cons(box mut paramlist, box Cons(box formalexp, box Nil)) => {
+          let mut formal_params = vec![];
+          {
+            let mut ptr = &paramlist;
+            loop {
+              match ptr {
+                &Cons(ref arg, ref rest) => {
+                  if let SymbolAtom(ref sym) = **arg {
+                    formal_params.push(sym.clone());
+                    ptr = rest;
+                  } else {
+                    return Err(format!("Bad lambda format"));
+                  }
+                },
+                _ => break,
+              }
+            }
+          }
+          FnLiteral {
+            formal_params,
+            body: Box::new(formalexp)
+          }
+        },
+        _ => return Err(format!("Bad lambda expression")),
+      },
+      "if" => match operands {
+        Cons(box test, box body) => {
+          let truth_value = test.truthy();
+          match (truth_value, body) {
+            (true, Cons(box consequent, _)) => consequent,
+            (false, Cons(_, box Cons(box alternative, _))) => alternative,
+            _ => return Err(format!("Bad if expression"))
+          }
+        },
+        _ => return Err(format!("Bad if expression"))
+      },
+      s => return Err(format!("Non-existent special form {}; this should never happen", s)),
+    })
+  }
+
+  fn apply(&mut self, function: Sexp, operands: Sexp) -> Result<Sexp, String> {
+    use self::Sexp::*;
+    match function {
+      FnLiteral { formal_params, body } => {
+        self.push_env();
+
+        let mut cur = operands;
+        for param in formal_params {
+          match cur {
+            Cons(box arg, box rest) => {
+              cur = rest;
+              self.set_var(param, arg);
+            },
+            _ => return Err(format!("Bad argument for function application")),
+          }
+        }
+        let result = self.eval(*body);
+        self.pop_env();
+        result
+      },
+      Primitive(prim) => {
+        let mut evaled_operands = Vec::new();
+        let mut cur_operand = operands;
+        loop {
+          match cur_operand {
+            Nil => break,
+            Cons(box l, box rest) => {
+              evaled_operands.push(self.eval(l)?);
+              cur_operand = rest;
+            },
+            _ => return Err(format!("Bad operands list"))
+          }
+        }
+
+        prim.apply(evaled_operands)
+      }
+      _ => return Err(format!("Bad type to apply")),
+    }
+  }
+}
+
+fn read(input: &str) -> Result<Vec<Sexp>, String> {
+  let mut chars: Peekable<Chars> = input.chars().peekable();
+  let mut tokens = tokenize(&mut chars).into_iter().peekable();
+  let mut sexps = Vec::new();
+  while let Some(_) = tokens.peek() {
+    sexps.push(parse(&mut tokens)?);
+  }
+  Ok(sexps)
+}
+
+#[derive(Debug)]
+enum Token {
+  LParen,
+  RParen,
+  Quote,
+  Word(String),
+  StringLiteral(String),
+  NumLiteral(u64),
+}
+
+//TODO make this notion of Eq more sophisticated
+#[derive(Debug, PartialEq, Clone)]
+enum Sexp {
+  SymbolAtom(String),
+  StringAtom(String),
+  NumberAtom(u64),
+  BoolAtom(bool),
+  Cons(Box<Sexp>, Box<Sexp>),
+  Nil,
+  FnLiteral {
+    formal_params: Vec<String>,
+    body: Box<Sexp>
+  },
+  Primitive(PrimitiveFn)
+}
+
+#[derive(Debug, PartialEq, Clone)]
+enum PrimitiveFn {
+  Plus, Minus, Mult, Div, Mod, Greater, Less, GreaterThanOrEqual, LessThanOrEqual, Display
+}
+
+impl PrimitiveFn {
+  fn apply(&self, evaled_operands: Vec<Sexp>) -> Result<Sexp, String> {
+    use self::Sexp::*;
+    use self::PrimitiveFn::*;
+    let op = self.clone();
+    Ok(match op {
+      Display => {
+        for arg in evaled_operands {
+          print!("{}\n", arg.print());
+        }
+        Nil
+      },
+      Plus | Mult => {
+        let mut result = match op { Plus => 0, Mult => 1, _ => unreachable!() };
+        for arg in evaled_operands {
+          if let NumberAtom(n) = arg {
+            if let Plus = op {
+              result += n;
+            } else if let Mult = op {
+              result *= n;
+            }
+          } else {
+            return Err(format!("Bad operand: {:?}", arg));
+          }
+        }
+        NumberAtom(result)
+      },
+      op => return Err(format!("Primitive op {:?} not implemented", op)),
+    })
+
+  }
+}
+
+impl Sexp {
+  fn print(&self) -> String {
+    use self::Sexp::*;
+    match self {
+      &BoolAtom(true) => format!("#t"),
+      &BoolAtom(false) => format!("#f"),
+      &SymbolAtom(ref sym) => format!("{}", sym),
+      &StringAtom(ref s) => format!("\"{}\"", s),
+      &NumberAtom(ref n) => format!("{}", n),
+      &Cons(ref car, ref cdr) => format!("({} . {})", car.print(), cdr.print()),
+      &Nil => format!("()"),
+      &FnLiteral { ref formal_params, .. } => format!("<lambda {:?}>", formal_params),
+      &Primitive(ref sym) => format!("<primitive \"{:?}\">", sym),
+    }
+  }
+
+  fn truthy(&self) -> bool {
+    use self::Sexp::*;
+    match self {
+      &BoolAtom(false) => false,
+      _ => true
+    }
+  }
+}
+
+fn tokenize(input: &mut Peekable<Chars>) -> Vec<Token> {
+  use self::Token::*;
+  let mut tokens = Vec::new();
+  loop {
+    match input.next() {
+      None => break,
+      Some('(') => tokens.push(LParen),
+      Some(')') => tokens.push(RParen),
+      Some('\'') => tokens.push(Quote),
+      Some(c) if c.is_whitespace() => continue,
+      Some(c) if c.is_numeric() => {
+        let tok: String = input.peeking_take_while(|next| next.is_numeric()).collect();
+        let n: u64 = format!("{}{}", c, tok).parse().unwrap();
+        tokens.push(NumLiteral(n));
+      },
+      Some('"') => {
+        let string: String = input.scan(false, |escape, cur_char| {
+          let seen_escape = *escape;
+          *escape = cur_char == '\\' && !seen_escape;
+          match (cur_char, seen_escape) {
+            ('"', false) => None,
+            ('\\', false) => Some(None),
+            (c, _) => Some(Some(c))
+          }
+        }).filter_map(|x| x).collect();
+        tokens.push(StringLiteral(string));
+      }
+      Some(c) => {
+        let sym: String = input.peeking_take_while(|next| {
+          match *next {
+            '(' | ')' => false,
+            c if c.is_whitespace() => false,
+            _ => true
+          }
+        }).collect();
+        tokens.push(Word(format!("{}{}", c, sym)));
+      }
+    }
+  }
+  tokens
+}
+
+fn parse(tokens: &mut Peekable<IntoIter<Token>>) -> Result<Sexp, String> {
+  use self::Token::*;
+  use self::Sexp::*;
+  match tokens.next() {
+    Some(Word(ref s)) if s == "#f" => Ok(BoolAtom(false)),
+    Some(Word(ref s)) if s == "#t" => Ok(BoolAtom(true)),
+    Some(Word(s)) => Ok(SymbolAtom(s)),
+    Some(StringLiteral(s)) => Ok(StringAtom(s)),
+    Some(LParen) => parse_sexp(tokens),
+    Some(RParen) => Err(format!("Unexpected ')'")),
+    Some(Quote) => {
+      let quoted = parse(tokens)?;
+      Ok(Cons(Box::new(SymbolAtom(format!("quote"))), Box::new(Cons(Box::new(quoted), Box::new(Nil)))))
+    },
+    Some(NumLiteral(n)) => Ok(NumberAtom(n)),
+    None => Err(format!("Unexpected end of input")),
+  }
+}
+
+fn parse_sexp(tokens: &mut Peekable<IntoIter<Token>>) -> Result<Sexp, String> {
+  use self::Token::*;
+  use self::Sexp::*;
+  let mut cell = Nil;
+  {
+    let mut cell_ptr = &mut cell;
+    loop {
+      match tokens.peek() {
+        None => return Err(format!("Unexpected end of input")),
+        Some(&RParen) => {
+          tokens.next();
+          break;
+        },
+        _ => {
+          let current = parse(tokens)?;
+          let new_cdr = Cons(Box::new(current), Box::new(Nil));
+          match cell_ptr {
+            &mut Cons(_, ref mut cdr) => **cdr = new_cdr,
+            &mut Nil => *cell_ptr  = new_cdr,
+            _ => unreachable!()
+          };
+
+          let old_ptr = cell_ptr;
+          let new_ptr: &mut Sexp = match old_ptr { &mut Cons(_, ref mut cdr) => cdr, _ => unreachable!() } as &mut Sexp;
+          cell_ptr = new_ptr;
+        }
+      }
+    }
+  }
+  Ok(cell)
+}
+

schala-codegen/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "schala-codegen"
+version = "0.1.0"
+authors = ["greg <greg.shuflin@protonmail.com>"]
+
+[dependencies]
+syn = { version = "0.13.1", features = ["full", "extra-traits"] }
+quote = "0.5"
+schala-repl = { path = "../schala-repl" }
+
+[lib]
+proc-macro = true

schala-codegen/src/lib.rs

@@ -0,0 +1,102 @@
+#![feature(trace_macros)]
+#![feature(proc_macro)]
+extern crate proc_macro;
+#[macro_use]
+extern crate quote;
+extern crate syn;
+
+extern crate schala_repl;
+
+use proc_macro::TokenStream;
+use syn::{Ident, Attribute, DeriveInput};
+
+fn extract_attribute_arg_by_name(name: &str, attrs: &Vec<Attribute>) -> Option<String> {
+  use syn::{Meta, Lit, MetaNameValue};
+  attrs.iter().map(|attr| attr.interpret_meta()).find(|meta| {
+    match meta {
+      &Some(Meta::NameValue(MetaNameValue { ident, .. })) if ident.as_ref() == name => true,
+      _ => false
+    }
+  }).and_then(|meta| {
+    match meta {
+      Some(Meta::NameValue(MetaNameValue { lit: Lit::Str(litstr), .. })) => Some(litstr.value()),
+      _ => None,
+    }
+  })
+}
+
+fn extract_attribute_list(name: &str, attrs: &Vec<Attribute>) -> Option<Vec<(Ident, Option<Vec<Ident>>)>> {
+  use syn::{Meta, MetaList, NestedMeta};
+  attrs.iter().find(|attr| {
+    match attr.path.segments.iter().nth(0) {
+      Some(segment) if segment.ident.as_ref() == name => true,
+      _ => false
+    }
+  }).and_then(|attr| {
+    match attr.interpret_meta() {
+      Some(Meta::List(MetaList { nested, .. })) => {
+        Some(nested.iter().map(|nested_meta| match nested_meta {
+          &NestedMeta::Meta(Meta::Word(ident)) => (ident, None),
+          &NestedMeta::Meta(Meta::List(MetaList { ident, nested: ref nested2, .. })) => {
+            let own_args = nested2.iter().map(|nested_meta2| match nested_meta2 {
+              &NestedMeta::Meta(Meta::Word(ident)) => ident,
+              _ => panic!("Bad format for doubly-nested attribute list")
+            }).collect();
+            (ident, Some(own_args))
+          },
+          _ => panic!("Bad format for nested list")
+        }).collect())
+      },
+      _ => panic!("{} must be a comma-delimited list surrounded by parens", name)
+    }
+  })
+}
+
+#[proc_macro_derive(ProgrammingLanguageInterface, attributes(LanguageName, SourceFileExtension, PipelineSteps))]
+pub fn derive_programming_language_interface(input: TokenStream) -> TokenStream {
+  let ast: DeriveInput = syn::parse(input).unwrap();
+  let name = &ast.ident;
+  let attrs = &ast.attrs;
+
+  let language_name: String = extract_attribute_arg_by_name("LanguageName", attrs).expect("LanguageName is required");
+  let file_ext = extract_attribute_arg_by_name("SourceFileExtension", attrs).expect("SourceFileExtension is required");
+  let passes = extract_attribute_list("PipelineSteps", attrs).expect("PipelineSteps are required");
+  let pass_idents = passes.iter().map(|x| x.0);
+
+  //let pass_names: Vec<String> = passes.iter().map(|pass| pass.0.to_string()).collect();
+  let pass_descriptors = passes.iter().map(|pass| {
+    let name = pass.0.to_string();
+    let opts: Vec<String> = match &pass.1 {
+      None => vec![],
+      Some(opts) => opts.iter().map(|o| o.to_string()).collect(),
+    };
+
+    quote! {
+      PassDescriptor {
+        name: #name.to_string(),
+        debug_options: vec![#(format!(#opts)),*]
+      }
+    }
+  });
+
+  let tokens = quote! {
+    use schala_repl::PassDescriptor;
+    impl ProgrammingLanguageInterface for #name {
+      fn get_language_name(&self) -> String {
+        #language_name.to_string()
+      }
+      fn get_source_file_suffix(&self) -> String {
+        #file_ext.to_string()
+      }
+      fn execute_pipeline(&mut self, input: &str, options: &EvalOptions) -> FinishedComputation {
+        let mut chain = pass_chain![self, options; #(#pass_idents),* ];
+        chain(input)
+      }
+      fn get_passes(&self) -> Vec<PassDescriptor> {
+        vec![ #(#pass_descriptors),* ]
+        //vec![ #(PassDescriptor { name: #pass_names.to_string(), debug_options: vec![] }),* ]
+      }
+    }
+  };
+  tokens.into()
+}

schala-lang/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "schala-lang"
+version = "0.1.0"
+authors = ["greg <greg.shuflin@protonmail.com>"]
+
+[dependencies]
+itertools = "0.5.8"
+take_mut = "0.1.3"
+maplit = "*"
+lazy_static = "0.2.8"
+
+schala-repl = { path = "../schala-repl" }
+schala-codegen = { path = "../schala-codegen" }

schala-lang/src/ast.rs

@@ -0,0 +1,180 @@
+use std::rc::Rc;
+
+use builtin::{BinOp, PrefixOp};
+
+#[derive(Debug, PartialEq)]
+pub struct AST(pub Vec<Statement>);
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum Statement {
+  ExpressionStatement(Expression),
+  Declaration(Declaration),
+}
+
+pub type Block = Vec<Statement>;
+
+pub type ParamName = Rc<String>;
+pub type InterfaceName = Rc<String>; //should be a singleton I think??
+pub type FormalParam = (ParamName, Option<TypeName>);
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum Declaration {
+  FuncSig(Signature),
+  FuncDecl(Signature, Block),
+  TypeDecl {
+    name: TypeSingletonName,
+    body: TypeBody,
+    mutable: bool
+  },
+  TypeAlias(Rc<String>, Rc<String>), //should have TypeSingletonName in it, or maybe just String, not sure
+  Binding {
+    name: Rc<String>,
+    constant: bool,
+    expr: Expression,
+  },
+  Impl {
+    type_name: TypeName,
+    interface_name: Option<InterfaceName>,
+    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<TypeName>,
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct TypeBody(pub Vec<Variant>);
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum Variant {
+  UnitStruct(Rc<String>),
+  TupleStruct(Rc<String>, Vec<TypeName>),
+  Record(Rc<String>, Vec<(Rc<String>, TypeName)>),
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct Expression(pub ExpressionType, pub Option<TypeName>);
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum TypeName {
+  Tuple(Vec<TypeName>),
+  Singleton(TypeSingletonName)
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct TypeSingletonName {
+  pub name: Rc<String>,
+  pub params: Vec<TypeName>,
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum ExpressionType {
+  NatLiteral(u64),
+  FloatLiteral(f64),
+  StringLiteral(Rc<String>),
+  BoolLiteral(bool),
+  BinExp(BinOp, Box<Expression>, Box<Expression>),
+  PrefixExp(PrefixOp, Box<Expression>),
+  TupleLiteral(Vec<Expression>),
+  Value(Rc<String>),
+  NamedStruct {
+    name: Rc<String>,
+    fields: Vec<(Rc<String>, Expression)>,
+  },
+  Call {
+    f: Box<Expression>,
+    arguments: Vec<Expression>,
+  },
+  Index {
+    indexee: Box<Expression>,
+    indexers: Vec<Expression>,
+  },
+  IfExpression {
+    discriminator: Box<Discriminator>,
+    body: Box<IfExpressionBody>,
+  },
+  WhileExpression {
+    condition: Option<Box<Expression>>,
+    body: Block,
+  },
+  ForExpression {
+    enumerators: Vec<Enumerator>,
+    body: Box<ForBody>,
+  },
+  Lambda {
+    params: Vec<FormalParam>,
+    body: Block,
+  },
+  ListLiteral(Vec<Expression>),
+}
+#[derive(Debug, PartialEq, Clone)]
+pub enum Discriminator {
+  Simple(Expression),
+  BinOp(Expression, BinOp)
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum IfExpressionBody {
+  SimpleConditional(Block, Option<Block>),
+  SimplePatternMatch(Pattern, Block, Option<Block>),
+  GuardList(Vec<GuardArm>)
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct GuardArm {
+  pub guard: Guard,
+  pub body: Block,
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum Guard {
+  Pat(Pattern),
+  HalfExpr(HalfExpr)
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct HalfExpr {
+  pub op: Option<BinOp>,
+  pub expr: ExpressionType,
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum Pattern {
+  Ignored,
+  TuplePattern(Vec<Pattern>),
+  Literal(PatternLiteral),
+  TupleStruct(Rc<String>, Vec<Pattern>),
+  Record(Rc<String>, Vec<(Rc<String>, Pattern)>),
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum PatternLiteral {
+  NumPattern {
+    neg: bool,
+    num: ExpressionType,
+  },
+  StringPattern(Rc<String>),
+  BoolPattern(bool),
+  VarPattern(Rc<String>)
+}
+
+#[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),
+}

schala-lang/src/builtin.rs

@@ -0,0 +1,138 @@
+use std::rc::Rc;
+use std::collections::HashMap;
+use std::fmt;
+
+use tokenizing::TokenType;
+use self::BuiltinTypeSpecifier::*;
+use self::BuiltinTConst::*;
+
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum BuiltinTypeSpecifier {
+  Const(BuiltinTConst),
+  Func(Box<BuiltinTypeSpecifier>, Box<BuiltinTypeSpecifier>),
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum BuiltinTConst {
+  Nat,
+  Int,
+  Float,
+  StringT,
+  Bool,
+}
+
+impl fmt::Display for BuiltinTypeSpecifier {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    write!(f, "{:?}", self)
+  }
+}
+
+#[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) -> &Rc<String> {
+    &self.sigil
+  }
+  pub fn from_sigil_token(tok: &TokenType) -> Option<BinOp> {
+    use self::TokenType::*;
+    let s = match tok {
+      Operator(op) => op,
+      Period => ".",
+      Pipe => "|",
+      Slash => "/",
+      LAngleBracket => "<",
+      RAngleBracket => ">",
+      _ => return None
+    };
+    Some(BinOp::from_sigil(s))
+  }
+  /*
+  pub fn get_type(&self) -> Result<Type, String> {
+    let s = self.sigil.as_str();
+    BINOPS.get(s).map(|x| x.0.clone()).ok_or(format!("Binop {} not found", s))
+  }
+  */
+  pub fn min_precedence() -> i32 {
+    i32::min_value()
+  }
+  pub fn get_precedence_from_token(op: &TokenType) -> Option<i32> {
+    use self::TokenType::*;
+    let s = match op {
+      Operator(op) => op,
+      Period => ".",
+      Pipe => "|",
+      Slash => "/",
+      LAngleBracket => "<",
+      RAngleBracket => ">",
+      _ => return None
+    };
+    let default = 10_000_000;
+    Some(BINOPS.get(s).map(|x| x.2.clone()).unwrap_or_else(|| {
+      println!("Warning: operator {} not defined", s);
+      default
+    }))
+  }
+}
+
+#[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) -> &Rc<String> {
+    &self.sigil
+  }
+  pub fn is_prefix(op: &str) -> bool {
+    PREFIX_OPS.get(op).is_some()
+  }
+  /*
+  pub fn get_type(&self) -> Result<Type, String> {
+    let s = self.sigil.as_str();
+    PREFIX_OPS.get(s).map(|x| x.0.clone()).ok_or(format!("Prefix op {} not found", s))
+  }
+  */
+}
+lazy_static! {
+  static ref PREFIX_OPS: HashMap<&'static str, (BuiltinTypeSpecifier, ())> = 
+    hashmap! {
+      "+" => (Func(bx!(Const(Int)),  bx!(Const(Int))), ()),
+      "-" => (Func(bx!(Const(Int)),  bx!(Const(Int))), ()),
+      "!" => (Func(bx!(Const(Bool)),  bx!(Const(Bool))), ()),
+    };
+}
+
+/* the second tuple member is a placeholder for when I want to make evaluation rules tied to the
+ * binop definition */
+lazy_static! {
+  static ref BINOPS: HashMap<&'static str, (BuiltinTypeSpecifier, (), i32)> =
+    hashmap! {
+      "+" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 10),
+      "-" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 10),
+      "*" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "/" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Float))))), (), 20),
+      "//" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20), //TODO change this to `quot`
+      "%" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "++" => (Func(bx!(Const(StringT)), bx!(Func(bx!(Const(StringT)), bx!(Const(StringT))))), (), 30),
+      "^" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "&" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "|" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      ">" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      ">=" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "<" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "<=" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "==" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "=" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "<=>" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+    };
+}

schala-lang/src/eval.rs

@@ -0,0 +1,482 @@
+
+use std::cell::RefCell;
+use std::rc::Rc;
+use std::fmt::Write;
+use std::io;
+
+use itertools::Itertools;
+
+use util::ScopeStack;
+use reduced_ast::{ReducedAST, Stmt, Expr, Lit, Func};
+use symbol_table::{SymbolSpec, Symbol, SymbolTable};
+
+pub struct State<'a> {
+  values: ScopeStack<'a, Rc<String>, ValueEntry>,
+  symbol_table_handle: Rc<RefCell<SymbolTable>>,
+}
+
+macro_rules! builtin_binding {
+  ($name:expr, $values:expr) => {
+    $values.insert(Rc::new(format!($name)), ValueEntry::Binding { constant: true, val: Node::Expr(Expr::Func(Func::BuiltIn(Rc::new(format!($name))))) });
+  }
+}
+
+//TODO add a more concise way of getting a new frame
+impl<'a> State<'a> {
+  pub fn new(symbol_table_handle: Rc<RefCell<SymbolTable>>) -> State<'a> {
+    let mut values = ScopeStack::new(Some(format!("global")));
+    builtin_binding!("print", values);
+    builtin_binding!("println", values);
+    builtin_binding!("getline", values);
+    State { values, symbol_table_handle }
+  }
+
+  pub fn debug_print(&self) -> String {
+    format!("Values: {:?}", self.values)
+  }
+}
+
+#[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()))),
+    }
+  }
+}
+
+#[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(name) => format!("<built-in function '{}'>", name),
+        UserDefined { name: None, .. } => format!("<function>"),
+        UserDefined { name: Some(name), .. } => format!("<function '{}'>", name),
+      },
+      Expr::Constructor { 
+        type_name: _, name, tag, arity,
+      } => if *arity == 0 {
+        format!("{}", name)
+      } else {
+        format!("<data constructor '{}'>", name)
+      },
+      Expr::Tuple(exprs) => paren_wrapped_vec(exprs.iter().map(|x| x.to_repl())),
+      _ => format!("{:?}", self),
+    }
+  }
+}
+
+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 } => 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)),
+        },
+        Val(v) => self.value(v),
+        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 } => {
+          let name = match val  {
+            Expr::Val(name) => name,
+            _ => return Err(format!("Trying to assign to a non-value")),
+          };
+
+          let constant = match self.values.lookup(&name) {
+            None => return Err(format!("{} 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))
+        },
+        Unit => Ok(Node::Expr(Unit)),
+        CaseMatch { box cond, alternatives } => match self.expression(Node::Expr(cond))? {
+          Node::PrimObject { name, tag, items } => {
+            for alt in alternatives {
+              if alt.tag.map(|t| t == tag).unwrap_or(true) {
+                let mut inner_state = State {
+                  values: self.values.new_scope(None),
+                  symbol_table_handle: self.symbol_table_handle.clone(),
+                };
+                for (bound_var, val) in alt.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() });
+                  }
+                }
+                return inner_state.block(alt.item)
+              }
+            }
+            return Err(format!("No matches found"));
+          },
+          Node::PrimTuple { .. } => Err(format!("Tuples don't work")),
+          Node::Expr(e) => Err(format!("Exprs don't work {:?}", e))
+        },
+        UnimplementedSigilValue => Err(format!("Sigil value eval not implemented"))
+      }
+    }
+  }
+
+  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 {} args", 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(sigil) => Ok(Node::Expr(self.apply_builtin(sigil, 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))),
+          symbol_table_handle: self.symbol_table_handle.clone(),
+        };
+        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, name: Rc<String>, args: Vec<Expr>) -> EvalResult<Expr> {
+    use self::Expr::*;
+    use self::Lit::*;
+    let evaled_args: Result<Vec<Expr>, String> = args.into_iter().map(|arg| {
+      match self.expression(Node::Expr(arg)) {
+        Ok(Node::Expr(e)) => Ok(e),
+        Ok(Node::PrimTuple { .. }) => Err(format!("Trying to apply a builtin to a tuple")),
+        Ok(Node::PrimObject { .. }) => Err(format!("Trying to apply a builtin to a primitive object")),
+        Err(e) => Err(e)
+      }
+    }).collect();
+    let evaled_args = evaled_args?;
+
+    Ok(match (name.as_str(), evaled_args.as_slice()) {
+      /* binops */
+      ("+", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l + r)),
+      ("++", &[Lit(StringLit(ref s1)), Lit(StringLit(ref s2))]) => Lit(StringLit(Rc::new(format!("{}{}", s1, s2)))),
+      ("-", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l - r)),
+      ("*", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l * r)),
+      ("/", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Float((l as f64)/ (r as f64))),
+      ("//", &[Lit(Nat(l)), Lit(Nat(r))]) => if r == 0 {
+        return Err(format!("divide by zero"));
+      } else {
+        Lit(Nat(l / r))
+      },
+      ("%", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l % r)),
+      ("^", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l ^ r)),
+      ("&", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l & r)),
+      ("|", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l | r)),
+
+      /* comparisons */
+      ("==", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Bool(l == r)),
+      ("==", &[Lit(Int(l)), Lit(Int(r))]) => Lit(Bool(l == r)),
+      ("==", &[Lit(Float(l)), Lit(Float(r))]) => Lit(Bool(l == r)),
+      ("==", &[Lit(Bool(l)), Lit(Bool(r))]) => Lit(Bool(l == r)),
+      ("==", &[Lit(StringLit(ref l)), Lit(StringLit(ref r))]) => Lit(Bool(l == r)),
+
+      ("<", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Bool(l < r)),
+      ("<", &[Lit(Int(l)), Lit(Int(r))]) => Lit(Bool(l < r)),
+      ("<", &[Lit(Float(l)), Lit(Float(r))]) => Lit(Bool(l < r)),
+
+      ("<=", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Bool(l <= r)),
+      ("<=", &[Lit(Int(l)), Lit(Int(r))]) => Lit(Bool(l <= r)),
+      ("<=", &[Lit(Float(l)), Lit(Float(r))]) => Lit(Bool(l <= r)),
+
+      (">", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Bool(l > r)),
+      (">", &[Lit(Int(l)), Lit(Int(r))]) => Lit(Bool(l > r)),
+      (">", &[Lit(Float(l)), Lit(Float(r))]) => Lit(Bool(l > r)),
+
+      (">=", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Bool(l >= r)),
+      (">=", &[Lit(Int(l)), Lit(Int(r))]) => Lit(Bool(l >= r)),
+      (">=", &[Lit(Float(l)), Lit(Float(r))]) => Lit(Bool(l >= r)),
+
+      /* prefix ops */
+      ("!", &[Lit(Bool(true))]) => Lit(Bool(false)),
+      ("!", &[Lit(Bool(false))]) => Lit(Bool(true)),
+      ("-", &[Lit(Nat(n))]) => Lit(Int(-1*(n as i64))),
+      ("-", &[Lit(Int(n))]) => Lit(Int(-1*(n as i64))),
+      ("+", &[Lit(Int(n))]) => Lit(Int(n)),
+      ("+", &[Lit(Nat(n))]) => Lit(Nat(n)),
+
+
+      /* builtin functions */
+      ("print", &[ref anything]) => {
+        print!("{}", anything.to_repl());
+        Expr::Unit
+      },
+      ("println", &[ref anything]) => {
+        println!("{}", anything.to_repl());
+        Expr::Unit
+      },
+      ("getline", &[]) => {
+        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())))
+      },
+      (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 value(&mut self, name: Rc<String>) -> EvalResult<Node> {
+    use self::ValueEntry::*;
+    use self::Func::*;
+    //TODO add a layer of indirection here to talk to the symbol table first, and only then look up
+    //in the values table
+
+    let symbol_table = self.symbol_table_handle.borrow();
+    let value = symbol_table.lookup_by_name(&name);
+    Ok(match value {
+      Some(Symbol { name, spec }) => match spec {
+        //TODO I'll need this type_name later to do a table lookup
+        SymbolSpec::DataConstructor { type_name: _type_name, type_args, .. } => {
+          if type_args.len() == 0 {
+            Node::PrimObject { name: name.clone(), tag: 0, items: vec![] }
+          } else {
+            return Err(format!("This data constructor thing not done"))
+          }
+        },
+        SymbolSpec::Func(_) => match self.values.lookup(&name) {
+          Some(Binding { val: Node::Expr(Expr::Func(UserDefined { name, params, body })), .. }) => {
+            Node::Expr(Expr::Func(UserDefined { name: name.clone(), params: params.clone(), body: body.clone() }))
+          },
+          _ => unreachable!(),
+        },
+      },
+      /* see if it's an ordinary variable TODO make variables go in symbol table */
+      None => match self.values.lookup(&name) {
+        Some(Binding { val, .. }) => val.clone(),
+        None => return Err(format!("Couldn't find value {}", name)),
+      }
+    })
+  }
+}
+
+#[cfg(test)]
+mod eval_tests {
+  use std::cell::RefCell;
+  use std::rc::Rc;
+  use symbol_table::SymbolTable;
+  use tokenizing::tokenize;
+  use parsing::parse;
+  use eval::State;
+
+  macro_rules! all_output {
+    ($string:expr) => {
+      {
+        let symbol_table = Rc::new(RefCell::new(SymbolTable::new()));
+        let mut state = State::new(symbol_table);
+        let ast = parse(tokenize($string)).0.unwrap();
+        state.symbol_table_handle.borrow_mut().add_top_level_symbols(&ast).unwrap();
+        let reduced = ast.reduce(&state.symbol_table_handle.borrow());
+        let all_output = state.evaluate(reduced, true);
+        all_output
+      }
+    }
+  }
+
+  macro_rules! fresh_env {
+    ($string:expr, $correct:expr) => {
+      {
+        let all_output = all_output!($string);
+        let ref output = all_output.last().unwrap();
+        assert_eq!(**output, Ok($correct.to_string()));
+      }
+    }
+  }
+
+  #[test]
+  fn test_basic_eval() {
+    fresh_env!("1 + 2", "3");
+    fresh_env!("let mut a = 1; a = 2", "Unit");
+    fresh_env!("let mut a = 1; a = 2; a", "2");
+    fresh_env!(r#"("a", 1 + 2)"#, r#"("a", 3)"#);
+  }
+
+  #[test]
+  fn function_eval() {
+    fresh_env!("fn oi(x) { x + 1 }; oi(4)", "5");
+    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()
+    "#;
+    fresh_env!(scope_ok, "10");
+    let scope_ok = r#"
+    let a = 20
+    fn haha() {
+      let a = 10
+      a
+    }
+    a
+    "#;
+    fresh_env!(scope_ok, "20");
+  }
+
+  #[test]
+  fn basic_patterns() {
+    let source = r#"
+type Option<T> = Some(T) | None
+let x = Some(9); if x is Some(q) then { q } else { 0 }"#;
+    fresh_env!(source, "9");
+
+    let source = r#"
+type Option<T> = Some(T) | None
+let x = None; if x is Some(q) then { q } else { 0 }"#;
+    fresh_env!(source, "0");
+  }
+}

schala-lang/src/lib.rs

@@ -0,0 +1,148 @@
+#![feature(trace_macros)]
+#![feature(slice_patterns, box_patterns, box_syntax)]
+extern crate itertools;
+#[macro_use]
+extern crate lazy_static;
+#[macro_use]
+extern crate maplit;
+#[macro_use]
+extern crate schala_repl;
+#[macro_use]
+extern crate schala_codegen;
+
+use std::cell::RefCell;
+use std::rc::Rc;
+
+use itertools::Itertools;
+use schala_repl::{ProgrammingLanguageInterface, EvalOptions, TraceArtifact, UnfinishedComputation, FinishedComputation};
+
+macro_rules! bx {
+  ($e:expr) => { Box::new($e) }
+}
+
+mod util;
+mod builtin;
+mod tokenizing;
+mod ast;
+mod parsing;
+mod symbol_table;
+mod typechecking;
+mod reduced_ast;
+mod eval;
+
+//trace_macros!(true);
+#[derive(ProgrammingLanguageInterface)]
+#[LanguageName = "Schala"]
+#[SourceFileExtension = "schala"]
+#[PipelineSteps(tokenizing, parsing(compact,expanded,trace), symbol_table, typechecking, ast_reducing, eval)]
+pub struct Schala {
+  state: eval::State<'static>,
+  symbol_table: Rc<RefCell<symbol_table::SymbolTable>>,
+  type_context: typechecking::TypeContext<'static>,
+}
+
+
+impl Schala {
+  fn new_blank_env() -> Schala {
+    let symbols = Rc::new(RefCell::new(symbol_table::SymbolTable::new()));
+    Schala {
+      symbol_table: symbols.clone(),
+      type_context: typechecking::TypeContext::new(symbols.clone()),
+      state: eval::State::new(symbols),
+    }
+  }
+
+  pub fn new() -> Schala {
+    let prelude = r#"
+type Option<T> = Some(T) | None
+type Color = Red | Green | Blue
+type Ord = LT | EQ | GT
+    "#;
+    let mut s = Schala::new_blank_env();
+    s.execute_pipeline(prelude, &EvalOptions::default());
+    s
+  }
+}
+
+fn tokenizing(_handle: &mut Schala, input: &str, comp: Option<&mut UnfinishedComputation>) -> Result<Vec<tokenizing::Token>, String> {
+  let tokens = tokenizing::tokenize(input);
+  comp.map(|comp| {
+    let token_string = tokens.iter().map(|t| format!("{:?}<L:{},C:{}>", t.token_type, t.offset.0, t.offset.1)).join(", ");
+    comp.add_artifact(TraceArtifact::new("tokens", 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(_handle: &mut Schala, input: Vec<tokenizing::Token>, comp: Option<&mut UnfinishedComputation>) -> Result<ast::AST, String> {
+
+  let (ast, trace) = parsing::parse(input);
+  comp.map(|comp| {
+    //TODO need to control which of these debug stages get added
+    let opt = comp.cur_debug_options.get(0).map(|s| s.clone());
+    match opt {
+      None => comp.add_artifact(TraceArtifact::new("ast", format!("{:?}", ast))),
+      Some(ref s) if s == "compact" => comp.add_artifact(TraceArtifact::new("ast", format!("{:?}", ast))),
+      Some(ref s) if s == "expanded" => comp.add_artifact(TraceArtifact::new("ast", format!("{:#?}", ast))),
+      Some(ref s) if s == "trace" => comp.add_artifact(TraceArtifact::new_parse_trace(trace)),
+      Some(ref x) => println!("Bad parsing debug option: {}", x),
+    };
+  });
+  ast.map_err(|err| err.msg)
+}
+
+fn symbol_table(handle: &mut Schala, input: ast::AST, comp: Option<&mut UnfinishedComputation>) -> Result<ast::AST, String> {
+  let add = handle.symbol_table.borrow_mut().add_top_level_symbols(&input);
+  match add {
+    Ok(()) => {
+      let artifact = TraceArtifact::new("symbol_table", handle.symbol_table.borrow().debug_symbol_table());
+      comp.map(|comp| comp.add_artifact(artifact));
+      Ok(input)
+    },
+    Err(msg) => Err(msg)
+  }
+}
+
+fn typechecking(handle: &mut Schala, input: ast::AST, comp: Option<&mut UnfinishedComputation>) -> Result<ast::AST, String> {
+  match handle.type_context.type_check_ast(&input) {
+    Ok(ty) => {
+      comp.map(|c| {
+        c.add_artifact(TraceArtifact::new("type_table", format!("{}", handle.type_context.debug_types())));
+        c.add_artifact(TraceArtifact::new("type_check", format!("{:?}", ty)));
+      });
+      Ok(input)
+    },
+    Err(msg) => {
+      comp.map(|comp| {
+        comp.add_artifact(TraceArtifact::new("type_table", format!("{}", handle.type_context.debug_types())));
+        comp.add_artifact(TraceArtifact::new("type_check", format!("Type error: {:?}", msg)));
+      });
+      Ok(input)
+    }
+  }
+}
+
+fn ast_reducing(handle: &mut Schala, input: ast::AST, comp: Option<&mut UnfinishedComputation>) -> Result<reduced_ast::ReducedAST, String> {
+  let ref symbol_table = handle.symbol_table.borrow();
+  let output = input.reduce(symbol_table);
+  comp.map(|comp| comp.add_artifact(TraceArtifact::new("ast_reducing", format!("{:?}", output))));
+  Ok(output)
+}
+
+fn eval(handle: &mut Schala, input: reduced_ast::ReducedAST, comp: Option<&mut UnfinishedComputation>) -> Result<String, String> {
+  comp.map(|comp| comp.add_artifact(TraceArtifact::new("value_state", 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
+}
+

schala-lang/src/reduced_ast.rs

@@ -0,0 +1,282 @@
+use std::rc::Rc;
+
+use ast::{AST, Statement, Expression, Declaration, Discriminator, IfExpressionBody, Pattern, PatternLiteral, Guard, HalfExpr};
+use symbol_table::{Symbol, SymbolSpec, SymbolTable};
+use builtin::{BinOp, PrefixOp};
+
+#[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),
+  Tuple(Vec<Expr>),
+  Func(Func),
+  Val(Rc<String>),
+  Constructor {
+    type_name: Rc<String>,
+    name: Rc<String>,
+    tag: usize,
+    arity: usize,
+  },
+  Call {
+    f: Box<Expr>,
+    args: Vec<Expr>,
+  },
+  Assign {
+    val: Box<Expr>,
+    expr: Box<Expr>,
+  },
+  Conditional {
+    cond: Box<Expr>,
+    then_clause: Vec<Stmt>,
+    else_clause: Vec<Stmt>,
+  },
+  CaseMatch {
+    cond: Box<Expr>,
+    alternatives: Vec<Alternative>
+  },
+  UnimplementedSigilValue
+}
+
+#[derive(Debug, Clone)]
+pub struct Alternative {
+  pub tag: Option<usize>,
+  pub guards: Vec<Expr>,
+  pub bound_vars: Vec<Option<Rc<String>>>, //order here is iconic to order in a tuple-like type, None is equivalent to ignored
+  pub item: Vec<Stmt>,
+}
+
+#[derive(Debug, Clone)]
+pub enum Lit {
+  Nat(u64),
+  Int(i64),
+  Float(f64),
+  Bool(bool),
+  StringLit(Rc<String>),
+}
+
+#[derive(Debug, Clone)]
+pub enum Func {
+  BuiltIn(Rc<String>),
+  UserDefined {
+    name: Option<Rc<String>>,
+    params: Vec<Rc<String>>,
+    body: Vec<Stmt>,
+  }
+}
+
+impl AST {
+  pub fn reduce(&self, symbol_table: &SymbolTable) -> ReducedAST {
+    let mut output = vec![];
+    for statement in self.0.iter() {
+      output.push(statement.reduce(symbol_table));
+    }
+    ReducedAST(output)
+  }
+}
+
+impl Statement {
+  fn reduce(&self, symbol_table: &SymbolTable) -> Stmt { 
+    use ast::Statement::*;
+    match self {
+      ExpressionStatement(expr) => Stmt::Expr(expr.reduce(symbol_table)),
+      Declaration(decl) => decl.reduce(symbol_table),
+    }
+  }
+}
+
+impl Expression {
+  fn reduce(&self, symbol_table: &SymbolTable) -> Expr {
+    use ast::ExpressionType::*;
+    let ref input = self.0;
+    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) => binop.reduce(symbol_table, lhs, rhs),
+      PrefixExp(op, arg) => op.reduce(symbol_table, arg),
+      Value(name) => match symbol_table.lookup_by_name(name) {
+        Some(Symbol { spec: SymbolSpec::DataConstructor { index, type_args, type_name}, .. }) => Expr::Constructor {
+          type_name: type_name.clone(),
+          name: name.clone(),
+          tag: index.clone(),
+          arity: type_args.len(),
+        },
+        _ => Expr::Val(name.clone()),
+      },
+      Call { f, arguments } => Expr::Call {
+        f: Box::new(f.reduce(symbol_table)),
+        args: arguments.iter().map(|arg| arg.reduce(symbol_table)).collect(),
+      },
+      TupleLiteral(exprs) => Expr::Tuple(exprs.iter().map(|e| e.reduce(symbol_table)).collect()),
+      IfExpression { discriminator, body } => reduce_if_expression(discriminator, body, symbol_table),
+      _ => Expr::UnimplementedSigilValue,
+    }
+  }
+}
+
+fn reduce_if_expression(discriminator: &Discriminator, body: &IfExpressionBody, symbol_table: &SymbolTable) -> Expr {
+  let cond = Box::new(match *discriminator {
+    Discriminator::Simple(ref expr) => expr.reduce(symbol_table),
+    Discriminator::BinOp(ref expr, ref binop) => {
+      panic!()
+    }
+  });
+  match *body {
+    IfExpressionBody::SimpleConditional(ref then_clause, ref else_clause) => {
+      let then_clause = then_clause.iter().map(|expr| expr.reduce(symbol_table)).collect();
+      let else_clause = match else_clause {
+        None => vec![],
+        Some(stmts) => stmts.iter().map(|expr| expr.reduce(symbol_table)).collect(),
+      };
+      Expr::Conditional { cond, then_clause, else_clause }
+    },
+    IfExpressionBody::SimplePatternMatch(ref pat, ref then_clause, ref else_clause) => {
+      let then_clause = then_clause.iter().map(|expr| expr.reduce(symbol_table)).collect();
+      let else_clause = match else_clause {
+        None => vec![],
+        Some(stmts) => stmts.iter().map(|expr| expr.reduce(symbol_table)).collect(),
+      };
+
+      let alternatives = vec![
+        pat.to_alternative(then_clause, symbol_table),
+        Alternative {
+          tag: None,
+          guards: vec![],
+          bound_vars: vec![],
+          item: else_clause,
+        },
+      ];
+
+      Expr::CaseMatch {
+        cond,
+        alternatives,
+      }
+    },
+    IfExpressionBody::GuardList(ref guard_arms) => {
+      let alternatives = guard_arms.iter().map(|arm| match arm.guard {
+        Guard::Pat(ref p) =>  {
+          let item = arm.body.iter().map(|expr| expr.reduce(symbol_table)).collect();
+          p.to_alternative(item, symbol_table)
+        },
+        Guard::HalfExpr(HalfExpr { op: _, expr: _ }) => {
+          unimplemented!()
+        }
+      }).collect();
+      Expr::CaseMatch { cond, alternatives }
+    }
+  }
+}
+
+impl Pattern {
+  fn to_alternative(&self, item: Vec<Stmt>, symbol_table: &SymbolTable) -> Alternative {
+    use self::Pattern::*;
+    match self {
+      TupleStruct(name, subpatterns) => {
+        let symbol = symbol_table.values.get(name).expect(&format!("Symbol {} not found", name));
+        let tag = match symbol.spec {
+          SymbolSpec::DataConstructor { index, .. } => index.clone(),
+          _ => panic!("Bad symbol"),
+        };
+
+        /*
+        let guards = patterns.iter().map(|p| match p {
+
+
+        });
+        */
+        let guards = unimplemented!();
+
+        let bound_vars = subpatterns.iter().map(|p| match p {
+          Literal(PatternLiteral::VarPattern(var)) => Some(var.clone()),
+          Ignored => None,
+          _ => None,
+        }).collect();
+        Alternative {
+          tag: Some(tag),
+          guards,
+          bound_vars,
+          item,
+        }
+      },
+      TuplePattern(_items) => {
+        unimplemented!()
+      },
+      Record(_name, _pairs) => {
+        unimplemented!()
+      },
+      Ignored => unimplemented!(),
+      /* "a constant appearing in a pattern can easily be eliminated by replacing it with a variable
+       * and adding a guard to the equation instead" -  Implementation of Functional Programming
+       * Languages Simon Peyton-Jones, p. 58 */
+      Literal(lit) => match lit {
+        PatternLiteral::NumPattern { neg, num } => unimplemented!(),
+        PatternLiteral::StringPattern(_s) => unimplemented!(),
+        PatternLiteral::BoolPattern(_b) => unimplemented!(),
+        PatternLiteral::VarPattern(_var) => unimplemented!(),
+      },
+    }
+  }
+}
+
+impl Declaration {
+  fn reduce(&self, symbol_table: &SymbolTable) -> Stmt {
+    use self::Declaration::*;
+    use ::ast::Signature;
+    match self {
+      Binding {name, constant, expr } => Stmt::Binding { name: name.clone(), constant: *constant, expr: expr.reduce(symbol_table) },
+      FuncDecl(Signature { name, params, .. }, statements) => Stmt::PreBinding {
+        name: name.clone(),
+        func: Func::UserDefined {
+          name: Some(name.clone()),
+          params: params.iter().map(|param| param.0.clone()).collect(),
+          body: statements.iter().map(|stmt| stmt.reduce(symbol_table)).collect(),
+        }
+      },
+      TypeDecl { .. } => Stmt::Noop,
+      TypeAlias(_, _) => Stmt::Noop,
+      Interface { .. } => Stmt::Noop,
+      Impl { .. } => Stmt::Expr(Expr::UnimplementedSigilValue),
+      _ => Stmt::Expr(Expr::UnimplementedSigilValue)
+    }
+  }
+}
+
+impl BinOp {
+  fn reduce(&self, symbol_table: &SymbolTable, lhs: &Box<Expression>, rhs: &Box<Expression>) -> Expr {
+    if **self.sigil() == "=" {
+      Expr::Assign {
+        val: Box::new(lhs.reduce(symbol_table)),
+        expr: Box::new(rhs.reduce(symbol_table)),
+      }
+    } else {
+      let f = Box::new(Expr::Func(Func::BuiltIn(self.sigil().clone())));
+      Expr::Call { f, args: vec![lhs.reduce(symbol_table), rhs.reduce(symbol_table)]}
+    }
+  }
+}
+
+impl PrefixOp {
+  fn reduce(&self, symbol_table: &SymbolTable, arg: &Box<Expression>) -> Expr {
+    let f = Box::new(Expr::Func(Func::BuiltIn(self.sigil().clone())));
+    Expr::Call { f, args: vec![arg.reduce(symbol_table)]}
+  }
+}

schala-lang/src/symbol_table.rs

@@ -0,0 +1,131 @@
+use std::collections::HashMap;
+use std::rc::Rc;
+use std::fmt;
+use std::fmt::Write;
+
+use ast;
+use typechecking::TypeName;
+
+//cf. p. 150 or so of Language Implementation Patterns
+pub struct SymbolTable {
+  pub values: HashMap<Rc<String>, Symbol> //TODO this will eventually have real type information
+}
+
+//TODO add various types of lookups here, maybe multiple hash tables internally? also make values
+//non-public
+impl SymbolTable {
+  pub fn new() -> SymbolTable {
+    SymbolTable { values: HashMap::new() }
+  }
+
+  pub fn lookup_by_name(&self, name: &Rc<String>) -> Option<&Symbol> {
+    self.values.get(name)
+  }
+}
+
+#[derive(Debug)]
+pub struct Symbol {
+  pub name: Rc<String>,
+  pub spec: SymbolSpec,
+}
+
+impl fmt::Display for Symbol {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    write!(f, "<Name: {}, Spec: {}>", self.name, self.spec)
+  }
+}
+
+#[derive(Debug)]
+pub enum SymbolSpec {
+  Func(Vec<TypeName>),
+  DataConstructor {
+    index: usize,
+    type_name: Rc<String>,
+    type_args: Vec<Rc<String>>,
+  },
+}
+
+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({})({:?} -> {})", index, type_args, 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> {
+    use self::ast::{Statement, TypeName, Variant, TypeSingletonName, TypeBody};
+    use self::ast::Declaration::*;
+    for statement in ast.0.iter() {
+      if let Statement::Declaration(decl) = statement {
+        match decl {
+          FuncSig(signature) | FuncDecl(signature, _) => {
+            let mut ch: char = 'a';
+            let mut types = vec![];
+            for param in signature.params.iter() {
+              match param {
+                (_, Some(_ty)) => {
+                  //TODO eventually handle this case different
+                  types.push(Rc::new(format!("{}", ch)));
+                  ch = ((ch as u8) + 1) as char;
+                },
+                (_, None) => {
+                  types.push(Rc::new(format!("{}", ch)));
+                  ch = ((ch as u8) + 1) as char;
+                }
+              }
+            }
+            let spec = SymbolSpec::Func(types);
+            self.values.insert(
+              signature.name.clone(),
+              Symbol { name: signature.name.clone(), spec }
+              );
+          },
+          //TODO figure out why _params isn't being used here
+          TypeDecl { name: TypeSingletonName { name, params: _params}, body: TypeBody(variants), mutable: _mutable, } => {
+            for (index, var) in variants.iter().enumerate() {
+              match var {
+                Variant::UnitStruct(variant_name) => {
+                  let spec = SymbolSpec::DataConstructor {
+                    index,
+                    type_name: name.clone(),
+                    type_args: vec![],
+                  };
+                  self.values.insert(variant_name.clone(), Symbol { name: variant_name.clone(), spec });
+                },
+                Variant::TupleStruct(variant_name, tuple_members) => {
+                  let type_args = tuple_members.iter().map(|type_name| match type_name {
+                    TypeName::Singleton(TypeSingletonName { name, ..}) => name.clone(),
+                    TypeName::Tuple(_) => unimplemented!(),
+                  }).collect();
+                  let spec = SymbolSpec::DataConstructor {
+                    index,
+                    type_name: name.clone(),
+                    type_args
+                  };
+                  let symbol = Symbol { name: variant_name.clone(), spec };
+                  self.values.insert(variant_name.clone(), symbol);
+                },
+                e => return Err(format!("{:?} not supported in typing yet", e)),
+              }
+            }
+          },
+          _ => ()
+        }
+      }
+    }
+    Ok(())
+  }
+  pub fn debug_symbol_table(&self) -> String {
+    let mut output = format!("Symbol table\n");
+    for (name, sym) in &self.values {
+      write!(output, "{} -> {}\n", name, sym).unwrap();
+    }
+    output
+  }
+}

schala-lang/src/tokenizing.rs

@@ -0,0 +1,315 @@
+use itertools::Itertools;
+use std::collections::HashMap;
+use std::rc::Rc;
+use std::iter::{Iterator, Peekable};
+use std::fmt;
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum TokenType {
+  Newline, Semicolon,
+
+  LParen, RParen,
+  LSquareBracket, RSquareBracket,
+  LAngleBracket, RAngleBracket,
+  LCurlyBrace, RCurlyBrace,
+  Pipe,
+
+  Comma, Period, Colon, Underscore,
+  Slash,
+
+  Operator(Rc<String>),
+  DigitGroup(Rc<String>), HexLiteral(Rc<String>), BinNumberSigil,
+  StrLiteral(Rc<String>),
+  Identifier(Rc<String>),
+  Keyword(Kw),
+
+  EOF,
+
+  Error(String),
+}
+use self::TokenType::*;
+
+impl fmt::Display for TokenType {
+  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
+}
+
+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,
+    };
+}
+
+#[derive(Debug, Clone)]
+pub struct Token {
+  pub token_type: TokenType,
+  pub offset: (usize, usize),
+}
+
+impl Token {
+  pub fn get_error(&self) -> Option<String> {
+    match self.token_type {
+      TokenType::Error(ref s) => Some(s.clone()),
+      _ => None,
+    }
+  }
+  pub fn to_string_with_metadata(&self) -> String {
+    format!("{}(L:{},c:{})", self.token_type, self.offset.0, self.offset.1)
+  }
+}
+
+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_idx, ch_idx, c)) = input.next() {
+    let cur_tok_type = 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),
+      c if c.is_digit(10) => handle_digit(c, &mut input),
+      c if c.is_alphabetic() || c == '_' => handle_alphabetic(c, &mut input), //TODO I'll probably have to rewrite this if I care about types being uppercase, also type parameterization
+      c if is_operator(&c) => handle_operator(c, &mut input),
+      unknown => Error(format!("Unexpected character: {}", unknown)),
+    };
+    tokens.push(Token { token_type: cur_tok_type, offset: (line_idx, ch_idx) });
+  }
+  tokens
+}
+
+fn handle_digit(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenType {
+  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>>) -> TokenType {
+  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 TokenType::Error(format!("Unclosed string")),
+    }
+  }
+  TokenType::StrLiteral(Rc::new(buf))
+}
+
+fn handle_alphabetic(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenType {
+  let mut buf = String::new();
+  buf.push(c);
+  if c == '_' && input.peek().map(|&(_, _, c)| { !c.is_alphabetic() }).unwrap_or(true) {
+    return TokenType::Underscore
+  }
+
+  loop {
+    match input.peek().map(|&(_, _, c)| { c }) {
+      Some(c) if c.is_alphanumeric() => {
+        input.next();
+        buf.push(c);
+      },
+      _ => break,
+    }
+  }
+
+  match KEYWORDS.get(buf.as_str()) {
+    Some(kw) => TokenType::Keyword(*kw),
+    None => TokenType::Identifier(Rc::new(buf)),
+  }
+}
+
+fn handle_operator(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenType {
+  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,
+          _ => 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
+      }
+    }
+  }
+  TokenType::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_types: Vec<TokenType> = a.into_iter().map(move |t| t.token_type).collect();
+    assert_eq!(token_types, vec![Keyword(Let), ident!("a"), Colon, ident!("A"),
+      LAngleBracket, ident!("B"), RAngleBracket, op!("="), ident!("c"), op!("++"), ident!("d")]);
+  }
+
+  #[test]
+  fn underscores() {
+    let token_types: Vec<TokenType> = tokenize("4_8").into_iter().map(move |t| t.token_type).collect();
+    assert_eq!(token_types, vec![digit!("4"), Underscore, digit!("8")]);
+  }
+
+  #[test]
+  fn comments() {
+    let token_types: Vec<TokenType> = tokenize("1  + /* hella /* bro */ */ 2").into_iter().map(move |t| t.token_type).collect();
+    assert_eq!(token_types, vec![digit!("1"), op!("+"), digit!("2")]);
+  }
+
+  #[test]
+  fn backtick_operators() {
+    let token_types: Vec<TokenType> = tokenize("1 `plus` 2").into_iter().map(move |t| t.token_type).collect();
+    assert_eq!(token_types, vec![digit!("1"), op!("plus"), digit!("2")]);
+  }
+}

schala-lang/src/type_check.rs

@@ -0,0 +1,445 @@
+use std::collections::HashMap;
+use std::rc::Rc;
+
+
+use parsing::{AST, Statement, Declaration, Signature, Expression, ExpressionType, Operation, Variant, TypeName, TypeSingletonName};
+
+// from Niko's talk
+/* fn type_check(expression, expected_ty) -> Ty {
+    let ty = bare_type_check(expression, expected_type);
+    if ty icompatible with expected_ty {
+        try_coerce(expression, ty, expected_ty)
+    } else {
+      ty
+    }
+  }
+
+  fn bare_type_check(exprssion, expected_type) -> Ty { ... }
+ */
+
+/* H-M ALGO NOTES
+from https://www.youtube.com/watch?v=il3gD7XMdmA
+(also check out http://dev.stephendiehl.com/fun/006_hindley_milner.html)
+
+typeInfer :: Expr a -> Matching (Type a)
+unify :: Type a -> Type b -> Matching (Type c)
+
+(Matching a) is a monad in which unification is done
+
+ex:
+
+typeInfer (If e1 e2 e3) = do
+    t1 <- typeInfer e1
+    t2 <- typeInfer e2
+    t3 <- typeInfer e3
+    _ <- unify t1 BoolType
+    unify t2 t3 -- b/c t2 and t3 have to be the same type
+
+typeInfer (Const (ConstInt _)) = IntType -- same for other literals
+
+--function application
+typeInfer (Apply f x) = do
+    tf <- typeInfer f
+    tx <- typeInfer x
+    case tf of
+        FunctionType t1 t2 -> do
+            _ <- unify t1 tx
+            return t2
+        _ -> fail "Not a function"
+
+--type annotation
+typeInfer (Typed x t) = do
+    tx <- typeInfer x
+    unify tx t
+
+--variable and let expressions - need to pass around a map of variable names to types here
+typeInfer :: [ (Var, Type Var) ] -> Expr Var -> Matching (Type Var)
+
+typeInfer ctx (Var x) = case (lookup x ctx) of
+    Just t -> return t
+    Nothing -> fail "Unknown variable"
+
+--let x = e1 in e2
+typeInfer ctx (Let x e1 e2) = do
+    t1 <- typeInfer ctx e1
+    typeInfer ((x, t1) :: ctx) e2
+
+--lambdas are complicated (this represents ʎx.e)
+typeInfer ctx (Lambda x e) = do
+    t1 <- allocExistentialVariable
+    t2 <- typeInfer ((x, t1) :: ctx) e
+    return $ FunctionType t1 t2 -- ie. t1 -> t2
+
+
+--to solve the problem of map :: (a -> b) -> [a] -> [b]
+when we use a variable whose type has universal tvars, convert those universal
+tvars to existential ones
+    -and each  distinct universal tvar needs to map to the same existential type
+
+-so we change typeinfer:
+typeInfer ctx (Var x) = do
+    case (lookup x ctx) of
+        Nothing -> ...
+        Just t -> do
+            let uvars = nub (toList t) -- nub removes duplicates, so this gets unique universally quantified variables
+            evars <- mapM (const allocExistentialVariable) uvars
+            let varMap = zip uvars evars
+            let vixVar varMap v = fromJust $ lookup v varMap
+            return (fmap (fixVar varMap) t)
+
+--how do we define unify??
+
+-recall, type signature is:
+unify :: Type a -> Type b -> Matching (Type c)
+unify BoolType BoolType = BoolType --easy, same for all constants
+unify (FunctionType t1 t2) (FunctionType t3 t4) = do
+    t5 <- unify t1 t3
+    t6 <- unify t2 t4
+    return $ FunctionType t5 t6
+unify (TVar a) (TVar b) = if a == b then TVar a else fail
+--existential types can be assigned another type at most once
+--some complicated stuff about hanlding existential types
+--everything else is a type error
+unify a b = fail
+
+
+SKOLEMIZATION - how you prevent an unassigned existential type variable from leaking!
+-before a type gets to global scope, replace all unassigned existential vars w/  new unique universal
+type variables
+
+*/
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum Type {
+  TVar(TypeVar),
+  TConst(TypeConst),
+  TFunc(Box<Type>, Box<Type>),
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum TypeVar {
+  Univ(Rc<String>),
+  Exist(u64),
+}
+impl TypeVar {
+  fn univ(label: &str) -> TypeVar {
+    TypeVar::Univ(Rc::new(label.to_string()))
+  }
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum TypeConst {
+  UserT(Rc<String>),
+  Integer,
+  Float,
+  StringT,
+  Boolean,
+  Unit,
+  Bottom,
+}
+
+type TypeCheckResult = Result<Type, String>;
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+struct PathSpecifier(Rc<String>);
+
+#[derive(Debug, PartialEq, Clone)]
+struct TypeContextEntry {
+  ty: Type,
+  constant: bool
+}
+
+pub struct TypeContext {
+  symbol_table: HashMap<PathSpecifier, TypeContextEntry>,
+  evar_table: HashMap<u64, Type>,
+  existential_type_label_count: u64
+}
+
+impl TypeContext {
+  pub fn new() -> TypeContext {
+    TypeContext {
+      symbol_table: HashMap::new(),
+      evar_table: HashMap::new(),
+      existential_type_label_count: 0,
+    }
+  }
+  pub fn add_symbols(&mut self, ast: &AST) {
+    use self::Declaration::*;
+    use self::Type::*;
+    use self::TypeConst::*;
+
+    for statement in ast.0.iter() {
+      match *statement {
+        Statement::ExpressionStatement(_) => (),
+        Statement::Declaration(ref decl) => match *decl {
+          FuncSig(_) => (),
+          Impl { .. } => (),
+          TypeDecl(ref type_constructor, ref body) => {
+            for variant in body.0.iter() {
+              let (spec, ty) = match variant {
+                &Variant::UnitStruct(ref data_constructor) => {
+                  let spec = PathSpecifier(data_constructor.clone());
+                  let ty = TConst(UserT(type_constructor.name.clone()));
+                  (spec, ty)
+                },
+                &Variant::TupleStruct(ref data_construcor, ref args) => {
+                  //TODO fix
+                  let arg = args.get(0).unwrap();
+                  let type_arg = self.from_anno(arg);
+                  let spec = PathSpecifier(data_construcor.clone());
+                  let ty = TFunc(Box::new(type_arg), Box::new(TConst(UserT(type_constructor.name.clone()))));
+                  (spec, ty)
+                },
+                &Variant::Record(_, _) => unimplemented!(),
+              };
+              let entry = TypeContextEntry { ty, constant: true };
+              self.symbol_table.insert(spec, entry);
+            }
+          },
+          TypeAlias { .. } => (),
+          Binding {ref name, ref constant, ref expr} => {
+            let spec = PathSpecifier(name.clone());
+            let ty = expr.1.as_ref()
+              .map(|ty| self.from_anno(ty))
+              .unwrap_or_else(|| { self.alloc_existential_type() }); // this call to alloc_existential is OK b/c a binding only ever has one type, so if the annotation is absent, it's fine to just make one de novo
+            let entry = TypeContextEntry { ty, constant: *constant };
+            self.symbol_table.insert(spec, entry);
+          },
+          FuncDecl(ref signature, _) => {
+            let spec = PathSpecifier(signature.name.clone());
+            let ty = self.from_signature(signature);
+            let entry = TypeContextEntry { ty, constant: true };
+            self.symbol_table.insert(spec, entry);
+          },
+        }
+      }
+    }
+  }
+  fn lookup(&mut self, binding: &Rc<String>) -> Option<TypeContextEntry> {
+    let key = PathSpecifier(binding.clone());
+    self.symbol_table.get(&key).map(|entry| entry.clone())
+  }
+  pub fn debug_symbol_table(&self) -> String  {
+    format!("Symbol table:\n {:?}\nEvar table:\n{:?}", self.symbol_table, self.evar_table)
+  }
+  fn alloc_existential_type(&mut self) -> Type {
+    let ret = Type::TVar(TypeVar::Exist(self.existential_type_label_count));
+    self.existential_type_label_count += 1;
+    ret
+  }
+
+  fn from_anno(&mut self, anno: &TypeName) -> Type {
+    use self::Type::*;
+    use self::TypeConst::*;
+
+    match anno {
+      &TypeName::Singleton(TypeSingletonName { ref name, .. }) => {
+        match name.as_ref().as_ref() {
+          "Int" => TConst(Integer),
+          "Float" => TConst(Float),
+          "Bool" => TConst(Boolean),
+          "String" => TConst(StringT),
+          s => TVar(TypeVar::Univ(Rc::new(format!("{}",s)))),
+        }
+      },
+      &TypeName::Tuple(ref items) => {
+        if items.len() == 1 {
+          TConst(Unit)
+        } else {
+          TConst(Bottom)
+        }
+      }
+    }
+  }
+
+  fn from_signature(&mut self, sig: &Signature) -> Type {
+    use self::Type::*;
+    use self::TypeConst::*;
+
+    //TODO this won't work properly until you make sure that all (universal) type vars in the function have the same existential type var
+    // actually this should never even put existential types into the symbol table at all
+
+    //this will crash if more than 5 arg function is used
+    let names = vec!["a", "b", "c", "d", "e", "f"];
+    let mut idx = 0;
+    
+    let mut get_type = || { let q = TVar(TypeVar::Univ(Rc::new(format!("{}", names.get(idx).unwrap())))); idx += 1; q };
+
+    let return_type = sig.type_anno.as_ref().map(|anno| self.from_anno(&anno)).unwrap_or_else(|| { get_type() });
+    if sig.params.len() == 0 {
+      TFunc(Box::new(TConst(Unit)), Box::new(return_type))
+    } else {
+      let mut output_type = return_type;
+      for p in sig.params.iter() {
+        let p_type = p.1.as_ref().map(|anno| self.from_anno(anno)).unwrap_or_else(|| { get_type() });
+        output_type = TFunc(Box::new(p_type), Box::new(output_type));
+      }
+      output_type
+    }
+  }
+
+  pub fn type_check(&mut self, ast: &AST) -> TypeCheckResult {
+    use self::Type::*;
+    use self::TypeConst::*;
+
+    let mut last = TConst(Unit);
+
+    for statement in ast.0.iter() {
+      match statement {
+        &Statement::Declaration(ref _decl) => {
+          //return Err(format!("Declarations not supported"));
+        },
+        &Statement::ExpressionStatement(ref expr) => {
+          last = self.infer(expr)?;
+        }
+      }
+    }
+    Ok(last)
+  }
+  fn infer(&mut self, expr: &Expression) -> TypeCheckResult {
+    match (&expr.0, &expr.1) {
+      (exprtype, &Some(ref anno)) => {
+        let tx = self.infer_no_anno(exprtype)?;
+        let ty = self.from_anno(anno);
+        self.unify(tx, ty)
+      },
+      (exprtype, &None) => self.infer_no_anno(exprtype),
+    }
+  }
+
+  fn infer_no_anno(&mut self, ex: &ExpressionType) -> TypeCheckResult { 
+    use self::ExpressionType::*;
+    use self::Type::*;
+    use self::TypeConst::*;
+
+    Ok(match ex {
+      &IntLiteral(_) => TConst(Integer),
+      &FloatLiteral(_) => TConst(Float),
+      &StringLiteral(_) => TConst(StringT),
+      &BoolLiteral(_) => TConst(Boolean),
+      &Value(ref name, _) => {
+        self.lookup(name)
+          .map(|entry| entry.ty)
+          .ok_or(format!("Couldn't find {}", name))?
+      },
+      &BinExp(ref op, ref lhs, ref rhs) => {
+        let t_lhs = self.infer(lhs)?;
+        match self.infer_op(op)? {
+          TFunc(t1, t2) => {
+            let _ = self.unify(t_lhs, *t1)?;
+            let t_rhs = self.infer(rhs)?;
+            let x = *t2;
+            match x {
+              TFunc(t3, t4) => {
+                let _ = self.unify(t_rhs, *t3)?;
+                *t4
+              },
+              _ => return Err(format!("Not a function type either")),
+            }
+          },
+          _ => return Err(format!("Op {:?} is not a function type", op)),
+        }
+      },
+      &Call { ref f, ref arguments } => {
+        let tf = self.infer(f)?;
+        let targ = self.infer(arguments.get(0).unwrap())?;
+        match tf {
+          TFunc(box t1, box t2) => {
+            let _ = self.unify(t1, targ)?;
+            t2
+          },
+          _ => return Err(format!("Not a function!")),
+        }
+      },
+      _ => TConst(Bottom),
+    })
+  }
+
+  fn infer_op(&mut self, op: &Operation) -> TypeCheckResult {
+    use self::Type::*;
+    use self::TypeConst::*;
+    macro_rules! binoptype {
+      ($lhs:expr, $rhs:expr, $out:expr) => { TFunc(Box::new($lhs), Box::new(TFunc(Box::new($rhs), Box::new($out)))) };
+    }
+
+    Ok(match (*op.0).as_ref() {
+      "+" => binoptype!(TConst(Integer), TConst(Integer), TConst(Integer)),
+      "++" => binoptype!(TConst(StringT), TConst(StringT), TConst(StringT)),
+      "-" => binoptype!(TConst(Integer), TConst(Integer), TConst(Integer)),
+      "*" => binoptype!(TConst(Integer), TConst(Integer), TConst(Integer)),
+      "/" => binoptype!(TConst(Integer), TConst(Integer), TConst(Integer)),
+      "%" => binoptype!(TConst(Integer), TConst(Integer), TConst(Integer)),
+      _ => TConst(Bottom)
+    })
+  }
+
+  fn unify(&mut self, t1: Type, t2: Type) -> TypeCheckResult {
+    use self::Type::*;
+    use self::TypeVar::*;
+
+    println!("Calling unify with `{:?}` and `{:?}`", t1, t2);
+
+    match (&t1, &t2) {
+      (&TConst(ref c1), &TConst(ref c2)) if c1 == c2 => Ok(TConst(c1.clone())),
+      (&TFunc(ref t1, ref t2), &TFunc(ref t3, ref t4)) => {
+        let t5 = self.unify(*t1.clone().clone(), *t3.clone().clone())?;
+        let t6 = self.unify(*t2.clone().clone(), *t4.clone().clone())?;
+        Ok(TFunc(Box::new(t5), Box::new(t6)))
+      },
+      (&TVar(Univ(ref a)), &TVar(Univ(ref b))) => {
+        if a == b {
+          Ok(TVar(Univ(a.clone())))
+        } else {
+          Err(format!("Couldn't unify universal types {} and {}", a, b))
+        }
+      },
+      //the interesting case!!
+      (&TVar(Exist(ref a)), ref t2) => {
+        let x = self.evar_table.get(a).map(|x| x.clone());
+        match x {
+          Some(ref t1) => self.unify(t1.clone().clone(), t2.clone().clone()),
+          None => {
+            self.evar_table.insert(*a, t2.clone().clone());
+            Ok(t2.clone().clone())
+          }
+        }
+      },
+      (ref t1, &TVar(Exist(ref a))) => {
+        let x = self.evar_table.get(a).map(|x| x.clone());
+        match x {
+          Some(ref t2) => self.unify(t2.clone().clone(), t1.clone().clone()),
+          None => {
+            self.evar_table.insert(*a, t1.clone().clone());
+            Ok(t1.clone().clone())
+          }
+        }
+      },
+      _ => Err(format!("Types {:?} and {:?} don't unify", t1, t2))
+    }
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::{Type, TypeVar, TypeConst, TypeContext};
+  use super::Type::*;
+  use super::TypeConst::*;
+  use schala_lang::parsing::{parse, tokenize};
+
+  macro_rules! type_test {
+    ($input:expr, $correct:expr) => {
+      {
+      let mut tc = TypeContext::new();
+      let ast = parse(tokenize($input)).0.unwrap() ;
+      tc.add_symbols(&ast);
+      assert_eq!($correct, tc.type_check(&ast).unwrap())
+      }
+    }
+  }
+
+  #[test]
+  fn basic_inference() {
+    type_test!("30", TConst(Integer));
+    type_test!("fn x(a: Int): Bool {}; x(1)", TConst(Boolean));
+  }
+}

schala-lang/src/typechecking.rs

@@ -0,0 +1,493 @@
+use std::cell::RefCell;
+use std::rc::Rc;
+use std::collections::HashMap;
+use std::fmt;
+use std::fmt::Write;
+/*
+use std::collections::hash_set::Union;
+use std::iter::Iterator;
+use itertools::Itertools;
+*/
+
+use ast;
+use util::ScopeStack;
+use symbol_table::{SymbolSpec, SymbolTable};
+
+pub type TypeName = Rc<String>;
+type TypeResult<T> = Result<T, String>;
+
+#[derive(Debug, PartialEq, Clone)]
+enum Type {
+  Const(TConst),
+  Var(TypeName),
+  Func(Vec<Type>),
+}
+
+#[derive(Debug, PartialEq, Clone)]
+enum TConst {
+  Unit,
+  Nat,
+  StringT,
+  //Custom(String)
+}
+
+#[derive(Debug, PartialEq, Clone)]
+struct Scheme {
+  names: Vec<TypeName>,
+  ty: Type,
+}
+
+impl fmt::Display for Scheme {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    write!(f, "∀{:?} . {:?}", self.names, self.ty)
+  }
+}
+
+#[derive(Debug, PartialEq, Clone)]
+struct Substitution(HashMap<TypeName, Type>);
+impl Substitution {
+  fn empty() -> Substitution {
+    Substitution(HashMap::new())
+  }
+}
+
+#[derive(Debug, PartialEq, Clone)]
+struct TypeEnv(HashMap<TypeName, Scheme>);
+
+impl TypeEnv {
+  fn default() -> TypeEnv {
+    TypeEnv(HashMap::new())
+  }
+
+  fn populate_from_symbols(&mut self, symbol_table: &SymbolTable) {
+    for (name, symbol) in symbol_table.values.iter() {
+      if let SymbolSpec::Func(ref type_names) = symbol.spec {
+        let mut ch: char = 'a';
+        let mut names = vec![];
+        for _ in type_names.iter() {
+          names.push(Rc::new(format!("{}", ch)));
+          ch = ((ch as u8) + 1) as char;
+        }
+
+        let sigma = Scheme {
+          names: names.clone(),
+          ty: Type::Func(names.into_iter().map(|n| Type::Var(n)).collect())
+        };
+        self.0.insert(name.clone(), sigma);
+      }
+    }
+  }
+}
+
+pub struct TypeContext<'a> {
+  values: ScopeStack<'a, TypeName, Type>,
+  symbol_table_handle: Rc<RefCell<SymbolTable>>,
+  global_env: TypeEnv
+}
+
+impl<'a> TypeContext<'a> {
+  pub fn new(symbol_table_handle: Rc<RefCell<SymbolTable>>) -> TypeContext<'static> {
+    TypeContext { values: ScopeStack::new(None), global_env: TypeEnv::default(), symbol_table_handle }
+  }
+
+  pub fn debug_types(&self) -> String {
+    let mut output = format!("Type environment\n");
+    for (name, scheme) in &self.global_env.0 {
+      write!(output, "{} -> {}\n", name, scheme).unwrap();
+    }
+    output
+  }
+
+  pub fn type_check_ast(&mut self, input: &ast::AST) -> Result<String, String> {
+    let ref symbol_table = self.symbol_table_handle.borrow();
+    self.global_env.populate_from_symbols(symbol_table);
+    let output = self.global_env.infer_block(&input.0)?;
+    Ok(format!("{:?}", output))
+  }
+}
+
+impl TypeEnv {
+  fn instantiate(&mut self, sigma: Scheme) -> Type {
+    match sigma {
+      Scheme { ty, .. } => ty,
+    }
+  }
+  fn generate(&mut self, ty: Type) -> Scheme {
+    Scheme {
+      names: vec![], //TODO incomplete
+      ty
+    }
+  }
+  fn infer_block(&mut self, block: &Vec<ast::Statement>) -> TypeResult<Type> {
+    let mut output = Type::Const(TConst::Unit);
+    for statement in block {
+      output = self.infer_statement(statement)?;
+    }
+    Ok(output)
+  }
+  fn infer_statement(&mut self, statement: &ast::Statement) -> TypeResult<Type> {
+    match statement {
+      ast::Statement::ExpressionStatement(expr) => self.infer_expr(expr),
+      ast::Statement::Declaration(decl) => self.infer_decl(decl)
+    }
+  }
+  fn infer_decl(&mut self, decl: &ast::Declaration) -> TypeResult<Type> {
+    use ast::Declaration::*;
+    match decl {
+      Binding { name, expr, .. } => {
+        let ty = self.infer_expr(expr)?;
+        let sigma = self.generate(ty);
+        self.0.insert(name.clone(), sigma);
+      },
+      _ => (),
+    }
+    Ok(Type::Const(TConst::Unit))
+  }
+  fn infer_expr(&mut self, expr: &ast::Expression) -> TypeResult<Type> {
+    match expr {
+      ast::Expression(expr, Some(anno)) => {
+        self.infer_exprtype(expr)
+      },
+      ast::Expression(expr, None) => {
+        self.infer_exprtype(expr)
+      }
+    }
+  }
+
+  fn infer_exprtype(&mut self, expr: &ast::ExpressionType) -> TypeResult<Type> {
+    use self::TConst::*;
+    use ast::ExpressionType::*;
+    Ok(match expr {
+      NatLiteral(_) => Type::Const(Nat),
+      StringLiteral(_) => Type::Const(StringT),
+      BinExp(op, lhs, rhs) => {
+
+        return Err(format!("NOTDONE"))
+      },
+      Call { f, arguments } =>  {
+
+        return Err(format!("NOTDONE"))
+      },
+      Value(name) => {
+        let s = match self.0.get(name) {
+          Some(sigma) => sigma.clone(),
+          None => return Err(format!("Unknown variable: {}", name))
+        };
+        self.instantiate(s)
+      },
+      _ => Type::Const(Unit)
+    })
+  }
+}
+
+
+/* GIANT TODO - use the rust im crate, unless I make this code way less haskell-ish after it's done
+  */
+
+/*
+
+
+pub type TypeResult<T> = Result<T, String>;
+*/
+
+/* TODO this should just check the name against a map, and that map should be pre-populated with
+ * types */
+/*
+impl parsing::TypeName {
+  fn to_type(&self) -> TypeResult<Type> {
+	use self::parsing::TypeSingletonName;
+	use self::parsing::TypeName::*;
+	use self::Type::*; use self::TConstOld::*;
+    Ok(match self {
+      Tuple(_) => return Err(format!("Tuples not yet implemented")),
+      Singleton(name) => match name {
+        TypeSingletonName { name, .. } => match &name[..] {
+          /*
+          "Nat" => Const(Nat),
+          "Int" => Const(Int),
+          "Float" => Const(Float),
+          "Bool" => Const(Bool),
+          "String" => Const(StringT),
+          */
+          n => Const(Custom(n.to_string()))
+        }
+      }
+    })
+  }
+}
+*/
+
+
+
+/*
+impl TypeContext {
+  pub fn type_check_ast(&mut self, ast: &parsing::AST) -> TypeResult<String> {
+    let ref block = ast.0;
+    let mut infer = Infer::default();
+    let env = TypeEnvironment::default();
+    let output = infer.infer_block(block, &env);
+    match output {
+      Ok(s) => Ok(format!("{:?}", s)),
+      Err(s) => Err(format!("Error: {:?}", s))
+    }
+  }
+}
+
+// this is the equivalent of the Haskell Infer monad
+#[derive(Debug, Default)]
+struct Infer {
+  _idents: u32,
+}
+
+#[derive(Debug)]
+enum InferError {
+  CannotUnify(MonoType, MonoType),
+  OccursCheckFailed(Rc<String>, MonoType),
+  UnknownIdentifier(Rc<String>),
+  Custom(String),
+}
+
+type InferResult<T> = Result<T, InferError>;
+
+
+impl Infer {
+  fn fresh(&mut self) -> MonoType {
+    let i = self._idents;
+    self._idents += 1;
+    let name = Rc::new(format!("{}", ('a' as u8 + 1) as char));
+    MonoType::Var(name)
+  }
+
+  fn unify(&mut self, a: MonoType, b: MonoType) -> InferResult<Substitution> {
+    use self::InferError::*; use self::MonoType::*;
+    Ok(match (a, b) {
+      (Const(ref a), Const(ref b)) if a == b => Substitution::new(),
+      (Var(ref name), ref var) => Substitution::bind_variable(name, var),
+      (ref var, Var(ref name)) => Substitution::bind_variable(name, var),
+      (Function(box a1, box b1), Function(box a2, box b2)) => {
+        let s1 = self.unify(a1, a2)?;
+        let s2 = self.unify(b1.apply_substitution(&s1), b2.apply_substitution(&s1))?;
+        s1.merge(s2)
+      },
+      (a, b) => return Err(CannotUnify(a, b))
+    })
+  }
+
+  fn infer_block(&mut self, block: &Vec<parsing::Statement>, env: &TypeEnvironment) -> InferResult<MonoType> {
+    use self::parsing::Statement;
+    let mut ret = MonoType::Const(TypeConst::Unit);
+    for statement in block.iter() {
+      ret = match statement {
+        Statement::ExpressionStatement(expr) => {
+          let (sub, ty) = self.infer_expr(expr, env)?;
+          //TODO handle substitution monadically
+
+          ty
+        }
+        Statement::Declaration(decl) => MonoType::Const(TypeConst::Unit),
+      }
+    }
+    Ok(ret)
+  }
+
+  fn infer_expr(&mut self, expr: &parsing::Expression, env: &TypeEnvironment) -> InferResult<(Substitution, MonoType)> {
+    use self::parsing::Expression;
+    match expr {
+      Expression(e, Some(anno)) => self.infer_annotated_expr(e, anno, env),
+      /*
+        let anno_ty = anno.to_type()?;
+        let ty = self.infer_exprtype(&e)?;
+        self.unify(ty, anno_ty)
+      },
+      */
+      Expression(e, None) => self.infer_exprtype(e, env)
+    }
+  }
+
+  fn infer_annotated_expr(&mut self, expr: &parsing::ExpressionType, anno: &parsing::TypeName, env: &TypeEnvironment) -> InferResult<(Substitution, MonoType)> {
+    Err(InferError::Custom(format!("exprtype not done: {:?}", expr)))
+  }
+  fn infer_exprtype(&mut self, expr: &parsing::ExpressionType, env: &TypeEnvironment) -> InferResult<(Substitution, MonoType)> {
+    use self::parsing::ExpressionType::*;
+    use self::TypeConst::*;
+    Ok(match expr {
+      NatLiteral(_) => (Substitution::new(), MonoType::Const(Nat)),
+      FloatLiteral(_) => (Substitution::new(), MonoType::Const(Float)),
+      StringLiteral(_) => (Substitution::new(), MonoType::Const(StringT)),
+      BoolLiteral(_) => (Substitution::new(), MonoType::Const(Bool)),
+      Value(name) => match env.lookup(name) {
+        Some(sigma) => {
+          let tau = self.instantiate(&sigma);
+          (Substitution::new(), tau)
+        },
+        None => return Err(InferError::UnknownIdentifier(name.clone())),
+      },
+      e => return Err(InferError::Custom(format!("Type inference for {:?} not done", e)))
+    })
+  }
+  fn instantiate(&mut self, sigma: &PolyType) -> MonoType {
+    let ref ty: MonoType = sigma.1;
+    let mut subst = Substitution::new();
+
+    for name in sigma.0.iter() {
+      let fresh_mvar = self.fresh();
+      let new = Substitution::bind_variable(name, &fresh_mvar);
+      subst = subst.merge(new);
+    }
+    ty.apply_substitution(&subst)
+  }
+}
+*/
+
+
+
+
+
+
+
+
+
+
+
+
+/* OLD STUFF DOWN HERE */
+
+
+
+/*
+impl TypeContext {
+  fn infer_block(&mut self, statements: &Vec<parsing::Statement>) -> TypeResult<Type> {
+    let mut ret_type = Type::Const(TConst::Unit);
+    for statement in statements {
+      ret_type = self.infer_statement(statement)?;
+    }
+    Ok(ret_type)
+  }
+
+  fn infer_statement(&mut self, statement: &parsing::Statement) -> TypeResult<Type> {
+    use self::parsing::Statement::*;
+    match statement {
+      ExpressionStatement(expr) => self.infer(expr),
+      Declaration(decl) => self.add_declaration(decl),
+    }
+  }
+  fn add_declaration(&mut self, decl: &parsing::Declaration) -> TypeResult<Type> {
+    use self::parsing::Declaration::*;
+    use self::Type::*;
+    match decl {
+      Binding { name, expr, .. } => {
+        let ty = self.infer(expr)?;
+        self.bindings.insert(name.clone(), ty);
+      },
+      _ => return Err(format!("other formats not done"))
+    }
+    Ok(Void)
+  }
+  fn infer(&mut self, expr: &parsing::Expression) -> TypeResult<Type> {
+    use self::parsing::Expression;
+    match expr {
+      Expression(e, Some(anno)) => {
+        let anno_ty = anno.to_type()?;
+        let ty = self.infer_exprtype(&e)?;
+        self.unify(ty, anno_ty)
+      },
+      Expression(e, None) => self.infer_exprtype(e)
+    }
+  }
+  fn infer_exprtype(&mut self, expr: &parsing::ExpressionType) -> TypeResult<Type> {
+    use self::parsing::ExpressionType::*;
+    use self::Type::*; use self::TConst::*;
+    match expr {
+      NatLiteral(_) => Ok(Const(Nat)),
+      FloatLiteral(_) => Ok(Const(Float)),
+      StringLiteral(_) => Ok(Const(StringT)),
+      BoolLiteral(_) => Ok(Const(Bool)),
+      BinExp(op, lhs, rhs) => { /* remember there are both the haskell convention talk and the write you a haskell ways to do this! */
+        match op.get_type()? {
+          Func(box t1, box Func(box t2, box t3)) => {
+            let lhs_ty = self.infer(lhs)?;
+            let rhs_ty = self.infer(rhs)?;
+            self.unify(t1, lhs_ty)?;
+            self.unify(t2, rhs_ty)?;
+            Ok(t3)
+          },
+          other => Err(format!("{:?} is not a binary function type", other))
+        }
+      },
+      PrefixExp(op, expr) => match op.get_type()? {
+        Func(box t1, box t2) => {
+          let expr_ty = self.infer(expr)?;
+          self.unify(t1, expr_ty)?;
+          Ok(t2)
+        },
+        other => Err(format!("{:?} is not a prefix op function type", other))
+      },
+      Value(name) => {
+        match self.bindings.get(name) {
+          Some(ty) => Ok(ty.clone()),
+          None => Err(format!("No binding found for variable: {}", name)),
+        }
+      },
+      Call { f, arguments } => {
+        let mut tf = self.infer(f)?;
+        for arg in arguments.iter() {
+          match tf {
+            Func(box t, box rest) => {
+              let t_arg = self.infer(arg)?;
+              self.unify(t, t_arg)?;
+              tf = rest;
+            },
+            other => return Err(format!("Function call failed to unify; last type: {:?}", other)),
+          }
+        }
+        Ok(tf)
+      },
+      TupleLiteral(expressions) => {
+        let mut types = vec![];
+        for expr in expressions {
+          types.push(self.infer(expr)?);
+        }
+        Ok(Sum(types))
+      },
+      _ => Err(format!("Type not yet implemented"))
+    }
+  }
+  fn unify(&mut self, t1: Type, t2: Type) -> TypeResult<Type> {
+    use self::Type::*;// use self::TConst::*;
+    match (t1, t2) {
+      (Const(ref a), Const(ref b)) if a == b => Ok(Const(a.clone())),
+      (a, b) => Err(format!("Types {:?} and {:?} don't unify", a, b))
+    }
+  }
+}
+*/
+
+
+#[cfg(test)]
+mod tests {
+  /*
+  use super::{Type, TConst, TypeContext};
+  use super::Type::*;
+  use super::TConst::*;
+  use std::rc::Rc;
+  use std::cell::RefCell;
+
+  macro_rules! type_test {
+    ($input:expr, $correct:expr) => {
+      {
+      let symbol_table = Rc::new(RefCell::new(SymbolTable::new()));
+      let mut tc = TypeContext::new(symbol_table);
+      let ast = ::ast::parse(::tokenizing::tokenize($input)).0.unwrap() ;
+      //tc.add_symbols(&ast);
+      assert_eq!($correct, tc.infer_block(&ast.0).unwrap())
+      }
+    }
+  }
+
+  #[test]
+  fn basic_inference() {
+    type_test!("30", Const(Nat));
+    //type_test!("fn x(a: Int): Bool {}; x(1)", TConst(Boolean));
+  }
+  */
+}

schala-lang/src/util.rs

@@ -0,0 +1,42 @@
+use std::collections::HashMap;
+use std::hash::Hash;
+use std::cmp::Eq;
+
+#[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),
+    }
+  }
+  //TODO rename new_scope
+  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,
+    }
+  }
+  pub fn get_name(&self) -> Option<&String> {
+    self.scope_name.as_ref()
+  }
+}
+

schala-repl/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "schala-repl"
+version = "0.1.0"
+authors = ["greg <greg.shuflin@protonmail.com>"]
+
+[dependencies]
+llvm-sys = "*"
+take_mut = "0.1.3"
+itertools = "0.5.8"
+getopts = "*"
+lazy_static = "0.2.8"
+maplit = "*"
+colored = "1.5"
+serde = "1.0.15"
+serde_derive = "1.0.15"
+serde_json = "1.0.3"
+rocket = "0.3.13"
+rocket_codegen = "0.3.13"
+rocket_contrib = "0.3.13"
+phf = "0.7.12"
+includedir = "0.2.0"
+linefeed = "0.5.0"
+regex = "0.2"
+
+[build-dependencies]
+includedir_codegen = "0.2.0"

schala-repl/build.rs

@@ -0,0 +1,10 @@
+extern crate includedir_codegen;
+
+use includedir_codegen::Compression;
+
+fn main() {
+    includedir_codegen::start("WEBFILES")
+        .dir("../static", Compression::Gzip)
+        .build("static.rs")
+        .unwrap();
+}

schala-repl/src/language.rs

@@ -0,0 +1,215 @@
+use std::collections::HashMap;
+use colored::*;
+use std::fmt::Write;
+use std::time;
+
+pub struct LLVMCodeString(pub String);
+
+#[derive(Debug, Default, Serialize, Deserialize)]
+pub struct EvalOptions {
+  pub execution_method: ExecutionMethod,
+  pub debug_passes: HashMap<String, PassDebugOptionsDescriptor>,
+}
+
+#[derive(Debug, Hash, PartialEq)]
+pub struct PassDescriptor {
+  pub name: String,
+  pub debug_options: Vec<String>
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct PassDebugOptionsDescriptor {
+  pub opts: Vec<String>,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub enum ExecutionMethod {
+  Compile,
+  Interpret,
+}
+impl Default for ExecutionMethod {
+  fn default() -> ExecutionMethod {
+    ExecutionMethod::Interpret
+  }
+}
+
+#[derive(Debug, Default)]
+pub struct UnfinishedComputation {
+  artifacts: Vec<(String, TraceArtifact)>,
+  pub durations: Vec<time::Duration>,
+  pub cur_debug_options: Vec<String>,
+}
+
+#[derive(Debug)]
+pub struct FinishedComputation {
+  artifacts: Vec<(String, TraceArtifact)>,
+  durations: Vec<time::Duration>,
+  text_output: Result<String, String>,
+}
+
+impl UnfinishedComputation {
+  pub fn add_artifact(&mut self, artifact: TraceArtifact) {
+    self.artifacts.push((artifact.stage_name.clone(), artifact));
+  }
+  pub fn finish(self, text_output: Result<String, String>) -> FinishedComputation {
+    FinishedComputation {
+      artifacts: self.artifacts,
+      text_output,
+      durations: self.durations
+    }
+  }
+  pub fn output(self, output: Result<String, String>) -> FinishedComputation {
+    FinishedComputation {
+      artifacts: self.artifacts,
+      text_output: output,
+      durations: self.durations,
+    }
+  }
+}
+
+impl FinishedComputation {
+  pub fn to_repl(&self) -> String {
+    let mut buf = String::new();
+    for (stage, artifact) in self.artifacts.iter() {
+      let color = artifact.text_color;
+      let stage = stage.color(color).bold();
+      let output = artifact.debug_output.color(color);
+      write!(&mut buf, "{}: {}\n", stage, output).unwrap();
+    }
+
+    let debug_timing = true;
+    if debug_timing {
+      write!(&mut buf, "Timing: ").unwrap();
+      for duration in self.durations.iter() {
+        let timing = (duration.as_secs() as f64) + (duration.subsec_nanos() as f64 * 1e-9);
+        write!(&mut buf, "{}s, ", timing).unwrap()
+      }
+      write!(&mut buf, "\n").unwrap();
+    }
+    match self.text_output {
+      Ok(ref output) => write!(&mut buf, "{}", output).unwrap(),
+      Err(ref err) => write!(&mut buf, "{} {}", "Error: ".red().bold(), err).unwrap(),
+    }
+    buf
+  }
+  pub fn to_noninteractive(&self) -> Option<String> {
+    match self.text_output {
+      Ok(_) => {
+        let mut buf = String::new();
+        for (stage, artifact) in self.artifacts.iter() {
+          let color = artifact.text_color;
+          let stage = stage.color(color).bold();
+          let output = artifact.debug_output.color(color);
+          write!(&mut buf, "{}: {}\n", stage, output).unwrap();
+        }
+        if buf == "" { None } else { Some(buf) }
+      },
+      Err(ref s) => Some(format!("{} {}", "Error: ".red().bold(), s))
+    }
+  }
+}
+
+#[derive(Debug)]
+pub struct TraceArtifact {
+  stage_name: String,
+  debug_output: String,
+  text_color: &'static str,
+}
+
+impl TraceArtifact {
+  pub fn new(stage: &str, debug: String) -> TraceArtifact {
+    let color = match stage {
+      "parse_trace"  | "ast" => "red",
+      "ast_reducing" => "red",
+      "tokens" => "green",
+      "type_check" => "magenta",
+      _ => "blue",
+    };
+    TraceArtifact { stage_name: stage.to_string(), debug_output: debug, text_color: color}
+  }
+
+  pub fn new_parse_trace(trace: Vec<String>) -> TraceArtifact {
+    let mut output = String::new();
+
+    for t in trace {
+      output.push_str(&t);
+      output.push_str("\n");
+    }
+
+    TraceArtifact { stage_name: "parse_trace".to_string(), debug_output: output, text_color: "red"}
+  }
+}
+
+pub trait ProgrammingLanguageInterface {
+  fn execute_pipeline(&mut self, _input: &str, _eval_options: &EvalOptions) -> FinishedComputation {
+    FinishedComputation { artifacts: vec![], text_output: Err(format!("Execution pipeline not done")), durations: vec![] }
+  }
+
+  fn get_language_name(&self) -> String;
+  fn get_source_file_suffix(&self) -> String;
+  fn get_passes(&self) -> Vec<PassDescriptor> {
+    vec![]
+  }
+  fn handle_custom_interpreter_directives(&mut self, _commands: &Vec<&str>) -> Option<String> {
+    None
+  }
+  fn custom_interpreter_directives_help(&self) -> String {
+    format!(">> No custom interpreter directives specified <<")
+  }
+}
+
+/* a pass_chain function signature looks like: 
+ * fn(&mut ProgrammingLanguageInterface, A, Option<&mut DebugHandler>) -> Result<B, String>
+ *
+ * TODO use some kind of failure-handling library to make this better
+ */
+
+#[macro_export]
+macro_rules! pass_chain {
+  ($state:expr, $options:expr; $($pass:path), *) => {
+    |text_input| {
+      let mut comp = UnfinishedComputation::default();
+      pass_chain_helper! { ($state, comp, $options); text_input $(, $pass)* }
+    }
+  };
+}
+
+#[macro_export]
+macro_rules! pass_chain_helper {
+  (($state:expr, $comp:expr, $options:expr); $input:expr, $pass:path $(, $rest:path)*) => {
+    {
+      use std::time;
+      use schala_repl::PassDebugOptionsDescriptor;
+      let pass_name = stringify!($pass);
+      let (output, duration) = {
+        let ref debug_map = $options.debug_passes;
+        let debug_handle = match debug_map.get(pass_name) {
+          Some(PassDebugOptionsDescriptor { opts }) => {
+            let ptr = &mut $comp;
+            ptr.cur_debug_options = opts.clone();
+            Some(ptr)
+          }
+          _ => None
+        };
+        let start = time::Instant::now();
+        let pass_output = $pass($state, $input, debug_handle);
+        let elapsed = start.elapsed();
+        (pass_output, elapsed)
+      };
+      $comp.durations.push(duration);
+      match output {
+        Ok(result) => pass_chain_helper! { ($state, $comp, $options); result $(, $rest)* },
+        Err(err) => {
+          $comp.output(Err(format!("Pass {} failed with {:?}", pass_name, err)))
+        }
+      }
+    }
+  };
+  // Done
+  (($state:expr, $comp:expr, $options:expr); $final_output:expr) => {
+    {
+      let final_output: FinishedComputation = $comp.finish(Ok($final_output));
+      final_output
+    }
+  };
+}

schala-repl/src/lib.rs

@@ -0,0 +1,561 @@
+#![feature(link_args)]
+#![feature(slice_patterns, box_patterns, box_syntax)]
+#![feature(plugin)]
+#![plugin(rocket_codegen)]
+extern crate getopts;
+extern crate linefeed;
+extern crate itertools;
+extern crate colored;
+
+#[macro_use]
+extern crate serde_derive;
+extern crate serde_json;
+extern crate rocket;
+extern crate rocket_contrib;
+extern crate includedir;
+extern crate phf;
+
+use std::path::Path;
+use std::fs::File;
+use std::io::{Read, Write};
+use std::process::exit;
+use std::default::Default;
+use std::fmt::Write as FmtWrite;
+
+use colored::*;
+use itertools::Itertools;
+
+mod language;
+mod webapp;
+pub mod llvm_wrap;
+
+const VERSION_STRING: &'static str = "0.1.0";
+
+include!(concat!(env!("OUT_DIR"), "/static.rs"));
+
+pub use language::{LLVMCodeString, ProgrammingLanguageInterface, EvalOptions,
+  ExecutionMethod, TraceArtifact, FinishedComputation, UnfinishedComputation, PassDebugOptionsDescriptor, PassDescriptor};
+
+pub type PLIGenerator = Box<Fn() -> Box<ProgrammingLanguageInterface> + Send + Sync>;
+
+pub fn repl_main(generators: Vec<PLIGenerator>) {
+  let languages: Vec<Box<ProgrammingLanguageInterface>> = generators.iter().map(|x| x()).collect();
+
+  let option_matches = program_options().parse(std::env::args()).unwrap_or_else(|e| {
+    println!("{:?}", e);
+    exit(1);
+  });
+
+  if option_matches.opt_present("list-languages") {
+    for lang in languages {
+      println!("{}", lang.get_language_name());
+    }
+    exit(1);
+  }
+
+  if option_matches.opt_present("help") {
+    println!("{}", program_options().usage("Schala metainterpreter"));
+    exit(0);
+  }
+
+  if option_matches.opt_present("webapp") {
+    webapp::web_main(generators);
+    exit(0);
+  }
+
+  let mut options = EvalOptions::default();
+  let debug_passes = if let Some(opts) = option_matches.opt_str("debug") {
+    let output: Vec<String> = opts.split_terminator(",").map(|s| s.to_string()).collect();
+    output
+  } else {
+    vec![]
+  };
+
+  let language_names: Vec<String> = languages.iter().map(|lang| {lang.get_language_name()}).collect();
+  let initial_index: usize =
+    option_matches.opt_str("lang")
+    .and_then(|lang| { language_names.iter().position(|x| { x.to_lowercase() == lang.to_lowercase() }) })
+    .unwrap_or(0);
+
+  options.execution_method = match option_matches.opt_str("eval-style") {
+    Some(ref s) if s == "compile" => ExecutionMethod::Compile,
+    _ => ExecutionMethod::Interpret,
+  };
+
+  match option_matches.free[..] {
+    [] | [_] => {
+      let mut repl = Repl::new(languages, initial_index);
+      repl.run();
+    }
+    [_, ref filename, _..] => {
+
+      run_noninteractive(filename, languages, options, debug_passes);
+    }
+  };
+}
+
+fn run_noninteractive(filename: &str, languages: Vec<Box<ProgrammingLanguageInterface>>, mut options: EvalOptions, debug_passes: Vec<String>) {
+  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();
+
+  for pass in debug_passes.into_iter() {
+    if let Some(_) = language.get_passes().iter().find(|desc| desc.name == pass) {
+      options.debug_passes.insert(pass, PassDebugOptionsDescriptor { opts: vec![] });
+    }
+  }
+
+  match options.execution_method {
+    ExecutionMethod::Compile => {
+      /*
+      let llvm_bytecode = language.compile(&buffer);
+      compilation_sequence(llvm_bytecode, filename);
+      */
+      panic!("Not ready to go yet");
+    },
+    ExecutionMethod::Interpret => {
+      let output = language.execute_pipeline(&buffer, &options);
+      output.to_noninteractive().map(|text| println!("{}", text));
+    }
+  }
+}
+
+#[derive(Clone)]
+enum CommandTree {
+  Terminal(String, Option<String>),
+  NonTerminal(String, Vec<CommandTree>, Option<String>),
+  Top(Vec<CommandTree>),
+}
+
+impl CommandTree {
+  fn term(s: &str, help: Option<&str>) -> CommandTree {
+    CommandTree::Terminal(s.to_string(), help.map(|x| x.to_string()))
+  }
+  fn get_cmd(&self) -> String {
+    match self {
+      CommandTree::Terminal(s, _) => s.to_string(),
+      CommandTree::NonTerminal(s, _, _) => s.to_string(),
+      CommandTree::Top(_) => "".to_string(),
+    }
+  }
+  fn get_help(&self) -> String {
+    match self {
+      CommandTree::Terminal(_, h) => h.as_ref().map(|h| h.clone()).unwrap_or(format!("")),
+      CommandTree::NonTerminal(_, _, h) => h.as_ref().map(|h| h.clone()).unwrap_or(format!("")),
+      CommandTree::Top(_) => "".to_string(),
+    }
+  }
+  fn get_children(&self) -> Vec<String> {
+    match self {
+      CommandTree::Terminal(_, _) => vec![],
+      CommandTree::NonTerminal(_, children, _) => children.iter().map(|x| x.get_cmd()).collect(),
+      CommandTree::Top(children) => children.iter().map(|x| x.get_cmd()).collect(),
+    }
+  }
+}
+
+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(&format!("{}", self.sigil)) {
+      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_children()).unwrap_or(vec![]).into_iter() {
+              if cmd.starts_with(word) {
+                completions.push(Completion {
+                    completion: format!("{}{}", if top { ":" } else { "" }, cmd),
+                    display: Some(cmd.clone()),
+                    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(_, _) => None,
+            });
+            command_tree = new_ptr;
+          }
+        }
+      }
+      Some(completions)
+    } else {
+      None
+    }
+  }
+}
+
+struct Repl {
+  options: EvalOptions,
+  languages: Vec<Box<ProgrammingLanguageInterface>>,
+  current_language_index: usize,
+  interpreter_directive_sigil: char,
+  line_reader: linefeed::interface::Interface<linefeed::terminal::DefaultTerminal>,
+}
+
+impl Repl {
+  fn new(languages: Vec<Box<ProgrammingLanguageInterface>>, initial_index: usize) -> Repl {
+    use linefeed::Interface;
+    let i = if initial_index < languages.len() { initial_index } else { 0 };
+
+    let line_reader = Interface::new("schala-repl").unwrap();
+
+    Repl {
+      options: Repl::get_options(),
+      languages: languages,
+      current_language_index: i,
+      interpreter_directive_sigil: ':',
+      line_reader
+    }
+  }
+
+  fn get_cur_language(&self) -> &ProgrammingLanguageInterface {
+    self.languages[self.current_language_index].as_ref()
+  }
+
+  fn get_options() -> EvalOptions {
+    File::open(".schala_repl")
+      .and_then(|mut file| {
+        let mut contents = String::new();
+        file.read_to_string(&mut contents)?;
+        Ok(contents)
+      })
+      .and_then(|contents| {
+        let options: EvalOptions = serde_json::from_str(&contents)?;
+        Ok(options)
+      }).unwrap_or(EvalOptions::default())
+  }
+
+  fn save_options(&self) {
+    let ref options = self.options;
+    let read = File::create(".schala_repl")
+      .and_then(|mut file| {
+        let buf = serde_json::to_string(options).unwrap();
+        file.write_all(buf.as_bytes())
+      });
+
+    if let Err(err) = read {
+      println!("Error saving .schala_repl file {}", err);
+    }
+  }
+
+  fn run(&mut self) {
+    use linefeed::ReadResult;
+
+    println!("Schala MetaInterpreter version {}", VERSION_STRING);
+    println!("Type {}help for help with the REPL", self.interpreter_directive_sigil);
+
+    self.line_reader.load_history(".schala_history").unwrap_or(());
+
+    loop {
+      let language_name = self.languages[self.current_language_index].get_language_name();
+      let directives = self.get_directives();
+      let tab_complete_handler = TabCompleteHandler::new(self.interpreter_directive_sigil, directives);
+      self.line_reader.set_completer(std::sync::Arc::new(tab_complete_handler));
+
+      let prompt_str = format!("{} >> ", language_name);
+      self.line_reader.set_prompt(&prompt_str);
+
+      match self.line_reader.read_line() {
+        Err(e) => {
+          println!("Terminal read error: {}", e);
+        },
+        Ok(ReadResult::Eof) => break,
+        Ok(ReadResult::Signal(_)) => break,
+        Ok(ReadResult::Input(ref input)) => {
+          self.line_reader.add_history_unique(input.to_string());
+          let output = match input.chars().nth(0) {
+            Some(ch) if ch == self.interpreter_directive_sigil => self.handle_interpreter_directive(input),
+            _ => Some(self.input_handler(input)),
+          };
+          if let Some(o) = output {
+            println!("=> {}", o);
+          }
+        }
+      }
+    }
+    self.line_reader.save_history(".schala_history").unwrap_or(());
+    self.save_options();
+    println!("Exiting...");
+  }
+
+  fn input_handler(&mut self, input: &str) -> String {
+    let ref mut language = self.languages[self.current_language_index];
+    let interpreter_output = language.execute_pipeline(input, &self.options);
+    interpreter_output.to_repl()
+  }
+
+  fn get_directives(&self) -> CommandTree {
+    let ref passes = self.get_cur_language().get_passes();
+
+    let passes_directives: Vec<CommandTree> = passes.iter()
+      .map(|pass_descriptor| {
+        let name = &pass_descriptor.name;
+        if pass_descriptor.debug_options.len() == 0 {
+          CommandTree::term(name, None)
+        } else {
+          let sub_opts: Vec<CommandTree> = pass_descriptor.debug_options.iter()
+            .map(|o| CommandTree::term(o, None)).collect();
+          CommandTree::NonTerminal(
+            name.clone(),
+            sub_opts,
+            None
+          )
+        }
+      }).collect();
+
+    CommandTree::Top(vec![
+      CommandTree::term("exit", Some("exit the REPL")),
+      CommandTree::term("quit", Some("exit the REPL")),
+      CommandTree::term("help", Some("Print this help message")),
+      CommandTree::NonTerminal(format!("debug"), vec![
+        CommandTree::term("passes", None),
+        CommandTree::NonTerminal(format!("show"), passes_directives.clone(), None),
+        CommandTree::NonTerminal(format!("hide"), passes_directives.clone(), None),
+      ], Some(format!("show or hide pass info for a given pass, or display the names of all passes"))),
+      CommandTree::NonTerminal(format!("lang"), vec![
+        CommandTree::term("next", None),
+        CommandTree::term("prev", None),
+        CommandTree::NonTerminal(format!("go"), vec![], None)//TODO
+      ], Some(format!("switch between languages, or go directly to a langauge by name"))),
+    ])
+  }
+
+  fn handle_interpreter_directive(&mut self, input: &str) -> Option<String> {
+    let mut iter = input.chars();
+    iter.next();
+    let commands: Vec<&str> = iter
+      .as_str()
+      .split_whitespace()
+      .collect();
+
+    let cmd: &str = match commands.get(0).clone() {
+      None => return None,
+      Some(s) => s
+    };
+
+    match cmd {
+      "exit" | "quit"  => {
+        self.save_options();
+        exit(0)
+      },
+      "lang" | "language" => match commands.get(1) {
+        Some(&"show") => {
+          let mut buf = String::new();
+          for (i, lang) in self.languages.iter().enumerate() {
+            write!(buf, "{}{}\n", if i == self.current_language_index { "* "} else { "" }, lang.get_language_name()).unwrap();
+          }
+          Some(buf)
+        },
+        Some(&"go") => match commands.get(2) {
+          None => Some(format!("Must specify a language name")),
+          Some(&desired_name) => {
+            for (i, _) in self.languages.iter().enumerate() {
+              let lang_name = self.languages[i].get_language_name();
+              if lang_name.to_lowercase() == desired_name.to_lowercase() {
+                self.current_language_index = i;
+                return Some(format!("Switching to {}", self.languages[self.current_language_index].get_language_name()));
+              }
+            }
+            Some(format!("Language {} not found", desired_name))
+          }
+        },
+        Some(&"next") | Some(&"n") => {
+          self.current_language_index = (self.current_language_index + 1) % self.languages.len();
+          Some(format!("Switching to {}", self.languages[self.current_language_index].get_language_name()))
+        },
+        Some(&"previous") | Some(&"p") | Some(&"prev") => { 
+          self.current_language_index = if self.current_language_index == 0 { self.languages.len() - 1 } else { self.current_language_index - 1 };
+          Some(format!("Switching to {}", self.languages[self.current_language_index].get_language_name()))
+        },
+        Some(e) => Some(format!("Bad `lang(uage)` argument: {}", e)),
+        None => Some(format!("Valid arguments for `lang(uage)` are `show`, `next`|`n`, `previous`|`prev`|`n`"))
+      },
+      "help" =>  {
+        let mut buf = String::new();
+        let ref lang = self.languages[self.current_language_index];
+        let directives = match self.get_directives() {
+            CommandTree::Top(children) => children,
+            _ => panic!("Top-level CommandTree not Top")
+        };
+
+        writeln!(buf, "MetaInterpreter options").unwrap();
+        writeln!(buf, "-----------------------").unwrap();
+
+        for directive in directives {
+          let trailer = " ";
+          writeln!(buf, "{}{}- {}", directive.get_cmd(), trailer, directive.get_help()).unwrap();
+        }
+
+        writeln!(buf, "").unwrap();
+        writeln!(buf, "Language-specific help for {}", lang.get_language_name()).unwrap();
+        writeln!(buf, "-----------------------").unwrap();
+        writeln!(buf, "{}", lang.custom_interpreter_directives_help()).unwrap();
+        Some(buf)
+      },
+      "debug" => self.handle_debug(commands),
+      e => self.languages[self.current_language_index]
+        .handle_custom_interpreter_directives(&commands)
+        .or(Some(format!("Unknown command: {}", e)))
+    }
+  }
+  fn handle_debug(&mut self, commands: Vec<&str>) -> Option<String> {
+    let passes = self.get_cur_language().get_passes();
+    match commands.get(1) {
+      Some(&"passes") => Some(
+        passes.into_iter()
+        .map(|desc| {
+          if self.options.debug_passes.contains_key(&desc.name) {
+            let color = "green";
+            format!("*{}", desc.name.color(color))
+          } else {
+            desc.name
+          }
+        })
+        .intersperse(format!(" -> "))
+        .collect()),
+      b @ Some(&"show") | b @ Some(&"hide") => {
+        let show = b == Some(&"show");
+        let debug_pass: String = match commands.get(2) {
+          Some(s) => s.to_string(),
+          None => return Some(format!("Must specify a stage to debug")),
+        };
+        let pass_opt = commands.get(3);
+        if let Some(desc) = passes.iter().find(|desc| desc.name == debug_pass) {
+          let mut opts = vec![];
+          if let Some(opt) = pass_opt {
+            opts.push(opt.to_string());
+          }
+          let msg = format!("{} debug for pass {}", if show { "Enabling" } else { "Disabling" }, debug_pass);
+          if show {
+            self.options.debug_passes.insert(desc.name.clone(), PassDebugOptionsDescriptor { opts });
+          } else {
+            self.options.debug_passes.remove(&desc.name);
+          }
+          Some(msg)
+        } else {
+          Some(format!("Couldn't find stage: {}", debug_pass))
+        }
+      },
+      _ => Some(format!("Unknown debug command"))
+    }
+  }
+}
+
+/*
+pub fn compilation_sequence(llvm_code: LLVMCodeString, sourcefile: &str) {
+    use std::process::Command;
+
+    let ll_filename = "out.ll";
+    let obj_filename = "out.o";
+    let q: Vec<&str> = sourcefile.split('.').collect();
+    let bin_filename = match &q[..] {
+        &[name, "maaru"] => name,
+        _ => panic!("Bad filename {}", sourcefile),
+    };
+
+    let LLVMCodeString(llvm_str) = llvm_code;
+
+    println!("Compilation process finished for {}", ll_filename);
+    File::create(ll_filename)
+        .and_then(|mut f| f.write_all(llvm_str.as_bytes()))
+        .expect("Error writing file");
+
+    let llc_output = Command::new("llc")
+        .args(&["-filetype=obj", ll_filename, "-o", obj_filename])
+        .output()
+        .expect("Failed to run llc");
+
+
+    if !llc_output.status.success() {
+        println!("{}", String::from_utf8_lossy(&llc_output.stderr));
+    }
+
+    let gcc_output = Command::new("gcc")
+        .args(&["-o", bin_filename, &obj_filename])
+        .output()
+        .expect("failed to run gcc");
+
+    if !gcc_output.status.success() {
+        println!("{}", String::from_utf8_lossy(&gcc_output.stdout));
+        println!("{}", String::from_utf8_lossy(&gcc_output.stderr));
+    }
+
+    for filename in [obj_filename].iter() {
+        Command::new("rm")
+            .arg(filename)
+            .output()
+            .expect(&format!("failed to run rm {}", filename));
+    }
+}
+*/
+
+fn program_options() -> getopts::Options {
+  let mut options = getopts::Options::new();
+  options.optopt("s",
+                 "eval-style",
+                 "Specify whether to compile (if supported) or interpret the language. If not specified, the default is language-specific",
+                 "[compile|interpret]"
+                 );
+  options.optflag("",
+                  "list-languages",
+                  "Show a list of all supported languages");
+  options.optopt("l",
+                 "lang",
+                 "Start up REPL in a language",
+                 "LANGUAGE");
+  options.optflag("h",
+                  "help",
+                  "Show help text");
+  options.optflag("w",
+                  "webapp",
+                  "Start up web interpreter");
+  options.optopt("d",
+                  "debug",
+                  "Debug a stage (l = tokenizer, a = AST, r = parse trace, s = symbol table)",
+                  "[l|a|r|s]");
+  options
+}

schala-repl/src/webapp.rs

@@ -0,0 +1,44 @@
+use rocket;
+use rocket::State;
+use rocket::response::Content;
+use rocket::http::ContentType;
+use rocket_contrib::Json;
+use language::{ProgrammingLanguageInterface, EvalOptions};
+use WEBFILES;
+use ::PLIGenerator;
+
+#[get("/")]
+fn index() -> Content<String> {
+  let path = "static/index.html";
+  let html_contents = String::from_utf8(WEBFILES.get(path).unwrap().into_owned()).unwrap();
+  Content(ContentType::HTML, html_contents)
+}
+
+#[get("/bundle.js")]
+fn js_bundle() -> Content<String> {
+  let path = "static/bundle.js";
+  let js_contents = String::from_utf8(WEBFILES.get(path).unwrap().into_owned()).unwrap();
+  Content(ContentType::JavaScript, js_contents)
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+struct Input {
+  source: String,
+}
+
+#[derive(Serialize, Deserialize)]
+struct Output {
+  text: String,
+}
+
+#[post("/input", format = "application/json", data = "<input>")]
+fn interpreter_input(input: Json<Input>, generators: State<Vec<PLIGenerator>>) -> Json<Output> {
+  let schala_gen = generators.get(0).unwrap();
+  let mut schala: Box<ProgrammingLanguageInterface> = schala_gen();
+  let code_output = schala.execute_pipeline(&input.source, &EvalOptions::default());
+  Json(Output { text: code_output.to_repl() })
+}
+
+pub fn web_main(language_generators: Vec<PLIGenerator>) {
+  rocket::ignite().manage(language_generators).mount("/", routes![index, js_bundle, interpreter_input]).launch();
+}

source_files/first.schala

@@ -1,2 +0,0 @@
-
-1 + 2

source_files/schala/does_scope_work.schala

@@ -0,0 +1,11 @@
+let c = 10
+
+fn add(a, b) {
+  let c = a + b
+  c
+}
+
+let mut b = 20
+
+println(add(1,2))
+println(c + b)

source_files/schala/first_program.schala

@@ -0,0 +1,17 @@
+fn main() {
+  let a = 10
+  let b = 20
+  a + b
+}
+
+//this is a one-line comment
+
+/* this is
+a multiline
+comment
+*/
+
+print(main())
+
+
+

source_files/schala/fizzbuzz.schala

@@ -0,0 +1,12 @@
+
+for n <- 1..=100 {
+  if n % 15 == 0 {
+    print("FizzBuzz")
+  } else if n % 5 == 0 {
+    print("Buzz")
+  } else if n % 3 == 0 {
+    print("Fizz")
+  } else {
+    print(n.to_string())
+  }
+}

source_files/schala/syntax_playground.schala

@@ -0,0 +1,114 @@
+
+fn main() {
+
+//comments are C-style
+/* nested comments /* are cool */ */
+
+}
+
+@annotations are with @-
+
+// variable expressions
+  var a: I32 = 20
+  const b: String = 20
+
+  there(); can(); be(); multiple(); statements(); per_line();
+
+  //string interpolation
+  const yolo = "I have ${a + b} people in my house"
+
+  // let expressions ??? not sure if I want this
+  let a = 10, b = 20, c = 30 in a + b + c
+
+  //list literal
+  const q = [1,2,3,4]
+
+  //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 */
+
+   //infinite loop
+   while {
+     if x() { break }
+     ...
+   }
+
+
+   //conditional loop
+   while conditionHolds() {
+      ...
+   }
+
+
+  //iteration over a variable
+  for i <- [1..1000]  {
+
+  } //return type is return type of block
+
+
+  //monadic decomposition
+  for {
+    a <- maybeInt();
+    s <- foo() 
+  } return {
+    a + s
+  } //return type is Monad<return type of block>
+
+/* end of for loops */
+
+
+
+/* conditionals/pattern matching */
+
+// "is" operator for "does this pattern match"
+
+x is Some(t) // type bool
+
+if x {
+  is Some(t) => {
+  },
+  is None => {
+
+  }
+}
+
+
+ //syntax is, I guess, for <expr> <brace-block>, where <expr> is a bool, or a <arrow-expr>
+
+ // type level alises
+ 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?
+ maybe introduce a 'newtype' keyword for this
+ */
+
+ //declaring types of all stripes
+ 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
+ 
+ trait Bashable { }
+ trait Luggable {
+  fn lug(self, a: Option<Self>)
+ }
+
+}
+
+
+// lambdas
+// ruby-style not rust-style
+const a: X -> Y -> Z = {|x,y|  }

source_files/schala/test.schala

@@ -0,0 +1,17 @@
+
+println(sua(4))
+
+fn sua(x): Int {
+  x + 10
+}
+
+
+//let a = getline()
+
+/*
+if a == "true" {
+  println("You typed true")
+} else {
+  println("You typed something else")
+}
+*/

source_files/test.rukka

@@ -0,0 +1,3 @@
+
+(display (+ 1 2))
+(display "Hello")

source_files/test.schala

@@ -1,98 +0,0 @@
-
-fn main() {
-
-# comments are scripting-style
-#{ but can also be
-
-}# blocks
-
-@annotations are with @-
-
-# variable expressions
-  var a: I32 = 20
-  const b: String = 20
-
-  there(); can(); be(); multiple(); statements(); per_line();
-
-  #string interpolation
-  const yolo = "I have ${a + b} people in my house"
-
-  # let expressions ??? not sure if I want this
-  let a = 10, b = 20, c = 30 in a + b + c
-
-  #list literal
-  const q = [1,2,3,4]
-
-  #lambda literal ?? maybe? not sure how this should work
-  q.map(|item| { item * 100 })
-
-  fn yolo(a: MyType, b: YourType): ReturnType<Param1, Param2> {
-    if a == 20 {
-      return "early"
-    }
-    var sex = 20
-    sex
-  }
-
-
-  for {
-  # infinite loop
-  }
-
-  #iteration over a variable
-  for i <- [1..1000]  {
-
-  } #return type is return type of block
-
-  #while loop
-  for a != 3 || fuckTard() {
-    break
-  } #return type is return type of block
-
-  #monadic decomposition
-  for {
-    a <- maybeInt();
-    s <- foo() 
-  } return {
-    a + s
-  } #return type is Monad<return type of block>
-
-  # let statements too!!
-  for (a = 20
-  b = fuck) {
-    a + b
-  }
-
-
-  # pattern-matching
-  match <expr> {
-    Some(a) => {
-
-    },
-    None => {
-
-    },
-  }
-
- #syntax is, I guess, for <expr> <brace-block>, where <expr> is a bool, or a <arrow-expr>
-
- # type level alises
- 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?
-# maybe introduce a 'newtype' keyword for this
-
- #declaring types of all stripes
- 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
- 
- trait Bashable { }
- trait Luggable {
-  fn lug(self, a: Option<Self>)
- }
-
-}

src/language.rs

@@ -1,110 +0,0 @@
-extern crate colored;
-
-use self::colored::*;
-
-#[derive(Debug)]
-pub struct TokenError {
-    pub msg: String,
-}
-
-impl TokenError {
-    pub fn new(msg: &str) -> TokenError {
-        TokenError { msg: msg.to_string() }
-    }
-}
-
-pub struct LLVMCodeString(pub String);
-
-#[derive(Debug, Default, Serialize, Deserialize)]
-pub struct EvalOptions {
-  pub debug_tokens: bool,
-  pub debug_parse: bool,
-  pub debug_type: bool,
-  pub debug_symbol_table: bool,
-  pub show_llvm_ir: bool,
-  pub trace_evaluation: bool,
-  pub compile: bool,
-}
-
-#[derive(Debug, Default)]
-pub struct ReplOutput {
-  output: String,
-  artifacts: Vec<TraceArtifact>
-}
-
-impl ReplOutput {
-  pub fn add_artifact(&mut self, artifact: TraceArtifact) {
-    self.artifacts.push(artifact);
-  }
-  pub fn add_output(&mut self, output: String) {
-    self.output = output;
-  }
-
-  pub fn to_string(&self) -> String {
-    let mut acc = String::new();
-    for line in self.artifacts.iter() {
-      acc.push_str(&line.debug_output.color(line.text_color).to_string());
-      acc.push_str(&"\n");
-    }
-    acc.push_str(&self.output);
-    acc
-  }
-
-  pub fn print_to_screen(&self) {
-    for line in self.artifacts.iter() {
-      println!("{}: {}", line.stage_name, line.debug_output);
-    }
-    println!("{}", self.output);
-  }
-}
-
-/*
-//TODO I'll probably wanna implement this later
-#[derive(Debug)]
-pub struct CompilationOutput {
-  output: LLVMCodeString,
-  artifacts: Vec<TraceArtifact>,
-}
-*/
-
-#[derive(Debug)]
-pub struct TraceArtifact {
-  stage_name: String,
-  debug_output: String,
-  text_color: &'static str,
-}
-
-impl TraceArtifact {
-  pub fn new(stage: &str, debug: String) -> TraceArtifact {
-    let color = match stage {
-      "parse_trace"  | "ast" => "red",
-      "tokens" => "green",
-      "type_check" => "magenta",
-      _ => "blue",
-    };
-    TraceArtifact { stage_name: stage.to_string(), debug_output: debug, text_color: color}
-  }
-
-  pub fn new_parse_trace(trace: Vec<String>) -> TraceArtifact {
-    let mut output = String::new();
-
-    for t in trace {
-      output.push_str(&t);
-      output.push_str("\n");
-    }
-
-    TraceArtifact { stage_name: "parse_trace".to_string(), debug_output: output, text_color: "red"}
-  }
-}
-
-pub trait ProgrammingLanguageInterface {
-  fn evaluate_in_repl(&mut self, input: &str, eval_options: &EvalOptions) -> ReplOutput;
-  fn get_language_name(&self) -> String;
-  fn get_source_file_suffix(&self) -> String;
-  fn compile(&mut self, _input: &str) -> LLVMCodeString {
-    LLVMCodeString("".to_string())
-  }
-  fn can_compile(&self) -> bool {
-    false
-  }
-}

src/main.rs

@@ -1,364 +1,20 @@
-#![feature(advanced_slice_patterns, slice_patterns, box_patterns, box_syntax)]
-#![feature(plugin)]
-#![plugin(rocket_codegen)]
-extern crate getopts;
-extern crate linefeed;
-extern crate itertools;
-#[macro_use]
-extern crate lazy_static;
-#[macro_use]
-extern crate maplit;
-#[macro_use]
-extern crate serde_derive;
-extern crate serde_json;
-extern crate rocket;
-extern crate rocket_contrib;
+extern crate schala_repl;
 
-use std::path::Path;
-use std::fs::File;
-use std::io::{Read, Write};
-use std::process::exit;
-use std::default::Default;
+extern crate maaru_lang;
+extern crate rukka_lang;
+extern crate robo_lang;
+extern crate schala_lang;
+use schala_repl::{PLIGenerator, repl_main};
 
-mod schala_lang;
-mod maaru_lang;
-mod robo_lang;
-
-mod language;
-use language::{ProgrammingLanguageInterface, EvalOptions, LLVMCodeString};
-
-mod webapp;
-mod llvm_wrap;
+extern { }
 
 fn main() {
-  let languages: Vec<Box<ProgrammingLanguageInterface>> =
-    vec![
-      Box::new(schala_lang::Schala::new()),
-      Box::new(maaru_lang::Maaru::new()),
-      Box::new(robo_lang::Robo::new()),
-    ];
-
-  let option_matches = program_options().parse(std::env::args()).unwrap_or_else(|e| {
-    println!("{:?}", e);
-    exit(1);
-  });
-
-  if option_matches.opt_present("list-languages") {
-    for lang in languages {
-      println!("{}", lang.get_language_name());
-    }
-    exit(1);
-  }
-
-  if option_matches.opt_present("help") {
-    println!("{}", program_options().usage("Schala metainterpreter"));
-    exit(0);
-  }
-
-  if option_matches.opt_present("webapp") {
-    webapp::web_main();
-    exit(0);
-  }
-
-  let language_names: Vec<String> = languages.iter().map(|lang| {lang.get_language_name()}).collect();
-  let initial_index: usize =
-    option_matches.opt_str("lang")
-    .and_then(|lang| { language_names.iter().position(|x| { *x == lang }) })
-    .unwrap_or(0);
-
-  let mut options = EvalOptions::default();
-  options.compile = match option_matches.opt_str("eval-style") {
-    Some(ref s) if s == "compile" => true,
-    _ => false
-  };
-
-  match option_matches.free[..] {
-    [] | [_] => {
-      let mut repl = Repl::new(languages, initial_index);
-      repl.options.show_llvm_ir = true; //TODO make this be configurable
-      repl.run();
-    }
-    [_, ref filename, _..] => {
-
-      run_noninteractive(filename, languages, options);
-    }
-  };
-}
-
-fn run_noninteractive(filename: &str, languages: Vec<Box<ProgrammingLanguageInterface>>, options: EvalOptions) {
-  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();
-
-  if options.compile {
-    if !language.can_compile() {
-      panic!("Trying to compile a non-compileable language");
-    } else {
-      let llvm_bytecode = language.compile(&buffer);
-      compilation_sequence(llvm_bytecode, filename);
-    }
-  } else {
-    let interpretor_output = language.evaluate_in_repl(&buffer, &options);
-    interpretor_output.print_to_screen();
-  }
-}
-
-type LineReader = linefeed::Reader<linefeed::terminal::DefaultTerminal>;
-struct Repl {
-  options: EvalOptions,
-  languages: Vec<Box<ProgrammingLanguageInterface>>,
-  current_language_index: usize,
-  interpreter_directive_sigil: char,
-  reader: LineReader,
-}
-
-impl Repl {
-  fn new(languages: Vec<Box<ProgrammingLanguageInterface>>, initial_index: usize) -> Repl {
-    let mut reader: linefeed::Reader<_> = linefeed::Reader::new("Metainterpreter").unwrap();
-    reader.set_prompt(">> ");
-    let i = if initial_index < languages.len() { initial_index } else { 0 };
-
-    Repl {
-      options: Repl::get_options(),
-      languages: languages,
-      current_language_index: i,
-      interpreter_directive_sigil: '.',
-      reader: reader,
-    }
-  }
-
-  fn get_options() -> EvalOptions {
-    File::open(".schala_repl")
-      .and_then(|mut file| {
-        let mut contents = String::new();
-        file.read_to_string(&mut contents)?;
-        Ok(contents)
-      })
-      .and_then(|contents| {
-        let options: EvalOptions = serde_json::from_str(&contents)?;
-        Ok(options)
-      }).unwrap_or(EvalOptions::default())
-  }
-
-  fn save_options(&self) {
-    let ref options = self.options;
-    let read = File::create(".schala_repl")
-      .and_then(|mut file| {
-        let buf = serde_json::to_string(options).unwrap();
-        file.write_all(buf.as_bytes())
-      });
-
-    if let Err(err) = read {
-      println!("Error saving .schala_repl file {}", err);
-    }
-  }
-
-  fn run(&mut self) {
-    use linefeed::ReadResult::*;
-    println!("MetaInterpreter v 0.05");
-    println!("Using language: {}", self.languages[self.current_language_index].get_language_name());
-    loop {
-      match self.reader.read_line() {
-        Err(e) => {
-          println!("Terminal read error: {}", e);
-        },
-        Ok(Eof) => {
-          break;
-        }
-        Ok(Input(ref input)) => {
-          self.reader.add_history(input.clone());
-          if self.handle_interpreter_directive(input) {
-            continue;
-          }
-          let output = self.input_handler(input);
-          println!("=> {}", output);
-        }
-        _ => (),
-      }
-    }
-    println!("Exiting...");
-  }
-
-  fn input_handler(&mut self, input: &str) -> String {
-    let ref mut language = self.languages[self.current_language_index];
-    let interpretor_output = language.evaluate_in_repl(input, &self.options);
-    interpretor_output.to_string()
-  }
-
-  fn handle_interpreter_directive(&mut self, input: &str) -> bool {
-    match input.chars().nth(0) {
-      Some(ch) if ch == self.interpreter_directive_sigil => (),
-      _ => return false
-    }
-
-    let mut iter = input.chars();
-    iter.next();
-    let trimmed_sigil: &str = iter.as_str();
-
-    let commands: Vec<&str> = trimmed_sigil
-      .split_whitespace()
-      .collect();
-
-    let cmd: &str = match commands.get(0).clone() {
-      None => return true,
-      Some(s) => s
-    };
-
-    match cmd {
-      "exit" | "quit"  => {
-        self.save_options();
-        exit(0)
-      },
-      "history"  => {
-        for item in self.reader.history() {
-          println!("{}", item);
-        }
-      },
-      "help" => {
-        println!("Commands:");
-        println!("exit | quit");
-        println!("lang [show|next|previous]");
-        println!("set [show|hide] [tokens|parse|symbols|eval|llvm]");
-      }
-      "lang" => {
-        match commands.get(1) {
-          Some(&"show") => {
-            for (i, lang) in self.languages.iter().enumerate() {
-              if i == self.current_language_index {
-                println!("* {}", lang.get_language_name());
-              } else {
-                println!("{}", lang.get_language_name());
-              }
-            }
-          },
-          Some(&"next") => {
-            self.current_language_index = (self.current_language_index + 1) % self.languages.len();
-            println!("Switching to {}", self.languages[self.current_language_index].get_language_name());
-          }
-          Some(&"prev") | Some(&"previous") => {
-            self.current_language_index = if self.current_language_index == 0 { self.languages.len() - 1 } else { self.current_language_index - 1 };
-            println!("Switching to {}", self.languages[self.current_language_index].get_language_name());
-          },
-          Some(e) => println!("Bad `lang` argument: {}", e),
-          None => println!("`lang` - valid arguments `show`, `next`, `prev`|`previous`"),
-        }
-      },
-      "set" => {
-        let show = match commands.get(1) {
-          Some(&"show") => true,
-          Some(&"hide") => false,
-          Some(e) => {
-            println!("Bad `set` argument: {}", e);
-            return true;
-          }
-          None => {
-            println!("`set` - valid arguments `show {{option}}`, `hide {{option}}`");
-            return true;
-          }
-        };
-        match commands.get(2) {
-          Some(&"tokens") => self.options.debug_tokens = show,
-          Some(&"parse") => self.options.debug_parse = show,
-          Some(&"symbols") => self.options.debug_symbol_table = show,
-          Some(&"eval") => {
-            //let ref mut language = self.languages[self.current_language_index];
-            //language.set_option("trace_evaluation", show);
-          },
-          Some(&"llvm") => self.options.show_llvm_ir = show,
-          Some(e) => {
-            println!("Bad `show`/`hide` argument: {}", e);
-            return true;
-          }
-          None => {
-            println!("`show`/`hide` requires an argument");
-            return true;
-          }
-        }
-      },
-      e => println!("Unknown command: {}", e)
-    }
-    return true;
-  }
-}
-
-pub fn compilation_sequence(llvm_code: LLVMCodeString, sourcefile: &str) {
-    use std::process::Command;
-
-    let ll_filename = "out.ll";
-    let obj_filename = "out.o";
-    let q: Vec<&str> = sourcefile.split('.').collect();
-    let bin_filename = match &q[..] {
-        &[name, "maaru"] => name,
-        _ => panic!("Bad filename {}", sourcefile),
-    };
-
-    let LLVMCodeString(llvm_str) = llvm_code;
-
-    println!("Compilation process finished for {}", ll_filename);
-    File::create(ll_filename)
-        .and_then(|mut f| f.write_all(llvm_str.as_bytes()))
-        .expect("Error writing file");
-
-    let llc_output = Command::new("llc")
-        .args(&["-filetype=obj", ll_filename, "-o", obj_filename])
-        .output()
-        .expect("Failed to run llc");
-
-
-    if !llc_output.status.success() {
-        println!("{}", String::from_utf8_lossy(&llc_output.stderr));
-    }
-
-    let gcc_output = Command::new("gcc")
-        .args(&["-o", bin_filename, &obj_filename])
-        .output()
-        .expect("failed to run gcc");
-
-    if !gcc_output.status.success() {
-        println!("{}", String::from_utf8_lossy(&gcc_output.stdout));
-        println!("{}", String::from_utf8_lossy(&gcc_output.stderr));
-    }
-
-    for filename in [obj_filename].iter() {
-        Command::new("rm")
-            .arg(filename)
-            .output()
-            .expect(&format!("failed to run rm {}", filename));
-    }
-}
-
-fn program_options() -> getopts::Options {
-  let mut options = getopts::Options::new();
-  options.optopt("s",
-                 "eval-style",
-                 "Specify whether to compile (if supported) or interpret the language. If not specified, the default is language-specific",
-                 "[compile|interpret]"
-                 );
-  options.optflag("",
-                  "list-languages",
-                  "Show a list of all supported languages");
-  options.optopt("l",
-                 "lang",
-                 "Start up REPL in a language",
-                 "LANGUAGE");
-  options.optflag("h",
-                  "help",
-                  "Show help text");
-  options.optflag("w",
-                  "webapp",
-                  "Start up web interpreter");
-  options
+  let generators: Vec<PLIGenerator> = vec![
+    Box::new(|| { Box::new(schala_lang::Schala::new())}),
+    Box::new(|| { Box::new(maaru_lang::Maaru::new())}),
+    Box::new(|| { Box::new(robo_lang::Robo::new())}),
+    Box::new(|| { Box::new(rukka_lang::Rukka::new())}),
+  ];
+  repl_main(generators);
 }
 

src/schala_lang/eval.rs

@@ -1,109 +0,0 @@
-use schala_lang::parsing::{AST, Statement, Declaration, Expression, ExpressionType, Operation};
-
-pub struct ReplState {
-}
-
-type EvalResult<T> = Result<T, String>;
-
-enum FullyEvaluatedExpr {
-  UnsignedInt(u64),
-  SignedInt(i64),
-  Float(f64),
-  Str(String),
-  Bool(bool),
-}
-
-impl ReplState {
-  pub fn new() -> ReplState {
-    ReplState { }
-  }
-
-  pub fn evaluate(&mut self, ast: AST) -> Vec<String> {
-    let mut acc = vec![];
-    for statement in ast.0 {
-      match self.eval_statement(statement) {
-        Ok(output) => {
-          if let Some(s) = output {
-            acc.push(s);
-          }
-        },
-        Err(error) => {
-          acc.push(format!("Error: {}", error));
-          return acc;
-        },
-      }
-    }
-    acc
-  }
-}
-
-impl ReplState {
-  fn eval_statement(&mut self, statement: Statement) -> EvalResult<Option<String>> {
-    use self::FullyEvaluatedExpr::*;
-    match statement {
-      Statement::ExpressionStatement(expr) => {
-        self.eval_expr(expr).map( |eval| {
-          match eval {
-            UnsignedInt(n) => Some(format!("{}", n)),
-            SignedInt(n) => Some(format!("{}", n)),
-            Float(f) => Some(format!("{}", f)),
-            Str(s) => Some(format!("\"{}\"", s)),
-            Bool(b) => Some(format!("{}", b)),
-          }
-        })
-      },
-      Statement::Declaration(decl) => {
-        self.eval_decl(decl).map(|_| None)
-      }
-    }
-  }
-
-  fn eval_decl(&mut self, _decl: Declaration) -> EvalResult<()> {
-    Err("Not implmemented".to_string())
-  }
-
-  fn eval_expr(&mut self, expr: Expression) -> EvalResult<FullyEvaluatedExpr> {
-    use self::ExpressionType::*;
-    use self::FullyEvaluatedExpr::*;
-
-    let expr_type = expr.0;
-    match expr_type {
-      IntLiteral(n) => Ok(UnsignedInt(n)),
-      FloatLiteral(f) => Ok(Float(f)),
-      StringLiteral(s) => Ok(Str(s.to_string())),
-      BoolLiteral(b) => Ok(Bool(b)),
-      PrefixExp(op, expr) => self.eval_prefix_exp(op, expr),
-      BinExp(op, lhs, rhs) => self.eval_binexp(op, lhs, rhs),
-      _ => Err(format!("Unimplemented")),
-    }
-  }
-
-  fn eval_binexp(&mut self, op: Operation, lhs: Box<Expression>, rhs: Box<Expression>) -> EvalResult<FullyEvaluatedExpr> {
-    use self::FullyEvaluatedExpr::*;
-    let evaled_lhs = self.eval_expr(*lhs)?;
-    let evaled_rhs = self.eval_expr(*rhs)?;
-    let opstr: &str = &op.0;
-    Ok(match (opstr, evaled_lhs, evaled_rhs) {
-      ("+", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l + r),
-      ("-", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l - r),
-      ("*", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l * r),
-      ("/", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l / r),
-      ("%", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l % r),
-      _ => return Err(format!("Runtime error: not yet implemented")),
-    })
-  }
-
-  fn eval_prefix_exp(&mut self, op: Operation, expr: Box<Expression>) -> EvalResult<FullyEvaluatedExpr> {
-    use self::FullyEvaluatedExpr::*;
-    let evaled_expr = self.eval_expr(*expr)?;
-    let opstr: &str = &op.0;
-
-    Ok(match (opstr, evaled_expr) {
-      ("!", Bool(true)) => Bool(false),
-      ("!", Bool(false)) => Bool(true),
-      ("-", UnsignedInt(n)) => SignedInt(-1*(n as i64)),
-      ("-", SignedInt(n)) => SignedInt(-1*(n as i64)),
-      _ => return Err(format!("Runtime error: not yet implemented")),
-    })
-  }
-}

src/schala_lang/mod.rs

@@ -1,95 +0,0 @@
-use itertools::Itertools;
-use language::{ProgrammingLanguageInterface, EvalOptions, TraceArtifact, ReplOutput};
-
-mod parsing;
-mod type_check;
-mod eval;
-
-use self::type_check::{TypeContext};
-
-pub struct Schala {
-  state: eval::ReplState,
-  type_context: TypeContext
-}
-
-impl Schala {
-  pub fn new() -> Schala {
-    Schala {
-      state: eval::ReplState::new(),
-      type_context: TypeContext::new(),
-    }
-  }
-}
-
-impl ProgrammingLanguageInterface for Schala {
-  fn get_language_name(&self) -> String {
-    "Schala".to_string()
-  }
-
-  fn get_source_file_suffix(&self) -> String {
-    format!("schala")
-  }
-
-  fn evaluate_in_repl(&mut self, input: &str, options: &EvalOptions) -> ReplOutput {
-    let mut output = ReplOutput::default();
-    let tokens = parsing::tokenize(input);
-    if options.debug_tokens {
-      let token_string = tokens.iter().map(|t| format!("{:?}<{}>", t.token_type, t.offset)).join(", ");
-      output.add_artifact(TraceArtifact::new("tokens", format!("{:?}", token_string)));
-
-    }
-
-    {
-      let token_errors: Vec<&String> = tokens.iter().filter_map(|t| t.get_error()).collect();
-      if token_errors.len() != 0 {
-        output.add_output(format!("Tokenization error: {:?}\n", token_errors));
-        return output;
-      }
-    }
-
-    let ast = match parsing::parse(tokens) {
-      (Ok(ast), trace) => {
-        if options.debug_parse {
-          output.add_artifact(TraceArtifact::new_parse_trace(trace));
-          output.add_artifact(TraceArtifact::new("ast", format!("{:?}", ast)));
-        }
-        ast
-      },
-      (Err(err), trace) => {
-        output.add_artifact(TraceArtifact::new_parse_trace(trace));
-        output.add_output(format!("Parse error: {:?}\n", err.msg));
-        return output;
-      }
-    };
-
-    self.type_context.add_symbols(&ast);
-
-    if options.debug_symbol_table {
-      let text = self.type_context.debug_symbol_table();
-      output.add_artifact(TraceArtifact::new("symbol_table", text));
-    }
-
-    match self.type_context.type_check(&ast) {
-      Ok(ty) => {
-        output.add_artifact(TraceArtifact::new("type_check", format!("type: {:?}", ty)));
-      },
-      Err(msg) => {
-        output.add_artifact(TraceArtifact::new("type_check", msg));
-        output.add_output(format!("Type error"));
-        return output;
-      }
-    }
-
-    let evaluation_output = self.state.evaluate(ast);
-    let mut acc = String::new();
-    let mut iter = evaluation_output.iter().peekable();
-    while let Some(s) = iter.next() {
-      acc.push_str(&s);
-      if let Some(_) = iter.peek() {
-        acc.push_str("\n");
-      }
-    }
-    output.add_output(acc);
-    return output;
-  }
-}

src/schala_lang/type_check.rs

@@ -1,211 +0,0 @@
-use std::collections::HashMap;
-use std::rc::Rc;
-
-use schala_lang::parsing::{AST, Statement, Declaration, Signature, Expression, ExpressionType, Operation, TypeName};
-
-#[derive(Debug, PartialEq, Eq, Hash)]
-struct PathSpecifier(Rc<String>);
-
-#[derive(Debug, PartialEq, Clone)]
-struct TypeContextEntry {
-  type_var: TypeVariable,
-  constant: bool
-}
-
-pub struct TypeContext {
-  symbol_table: HashMap<PathSpecifier, TypeContextEntry>,
-  existential_type_label_count: u64
-}
-
-impl TypeContext {
-  pub fn new() -> TypeContext {
-    TypeContext {
-      symbol_table: HashMap::new(),
-      existential_type_label_count: 0,
-    }
-  }
-  pub fn add_symbols(&mut self, ast: &AST) {
-    use self::Declaration::*;
-
-    for statement in ast.0.iter() {
-      match *statement {
-        Statement::ExpressionStatement(_) => (),
-        Statement::Declaration(ref decl) => {
-          match *decl {
-            FuncSig(_) => (),
-            Impl { .. } => (),
-            TypeDecl { .. } => (),
-            TypeAlias { .. } => (),
-            Binding {ref name, ref constant, ref expr} => {
-              let spec = PathSpecifier(name.clone());
-              let type_var = expr.1.as_ref()
-                .map(|ty| self.from_anno(ty))
-                .unwrap_or_else(|| { self.get_existential_type() });
-              let entry = TypeContextEntry { type_var, constant: *constant };
-              self.symbol_table.insert(spec, entry);
-            },
-            FuncDecl(ref signature, _) => {
-              let spec = PathSpecifier(signature.name.clone());
-              let type_var = self.from_signature(signature);
-              let entry = TypeContextEntry { type_var, constant: true };
-              self.symbol_table.insert(spec, entry);
-            },
-          }
-        }
-      }
-    }
-  }
-  fn lookup(&mut self, binding: &Rc<String>) -> Option<TypeContextEntry> {
-    let key = PathSpecifier(binding.clone());
-    self.symbol_table.get(&key).map(|entry| entry.clone())
-  }
-  pub fn debug_symbol_table(&self) -> String  {
-    format!("Symbol table:\n {:?}", self.symbol_table)
-  }
-  fn get_existential_type(&mut self) -> TypeVariable {
-    let ret = TypeVariable::Exist(self.existential_type_label_count);
-    self.existential_type_label_count += 1;
-    ret
-  }
-
-  fn from_anno(&mut self, anno: &TypeName) -> TypeVariable {
-    use self::TypeVariable::*;
-    use self::UVar::*;
-
-    match anno {
-      &TypeName::Singleton { ref name, .. } => {
-        match name.as_ref().as_ref() {
-          "Int" => Univ(Integer),
-          "Bool" => Univ(Boolean),
-          _ => self.get_existential_type()
-        }
-      },
-      _ => Univ(Bottom),
-    }
-  }
-
-  fn from_signature(&mut self, sig: &Signature) -> TypeVariable {
-    use self::TypeVariable::Univ;
-    use self::UVar::{Unit, Function};
-    let return_type = sig.type_anno.as_ref().map(|anno| self.from_anno(&anno)).unwrap_or_else(|| { self.get_existential_type() });
-    if sig.params.len() == 0 {
-      Univ(Function(Box::new(Univ(Unit)), Box::new(return_type)))
-    } else {
-      let mut output_type = return_type;
-      for p in sig.params.iter() {
-        let p_type = p.1.as_ref().map(|anno| self.from_anno(anno)).unwrap_or_else(|| { self.get_existential_type() });
-        output_type = Univ(Function(Box::new(p_type), Box::new(output_type)));
-      }
-      output_type
-    }
-  }
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum TypeVariable {
-  Univ(UVar),
-  Exist(u64),
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum UVar {
-  Integer,
-  Float,
-  Boolean,
-  Unit,
-  Function(Box<TypeVariable>, Box<TypeVariable>),
-  Bottom,
-}
-
-type TypeCheckResult = Result<TypeVariable, String>;
-
-// from Niko's talk
-/* fn type_check(expression, expected_ty) -> Ty {
-    let ty = bare_type_check(expression, expected_type);
-    if ty icompatible with expected_ty {
-        try_coerce(expression, ty, expected_ty)
-    } else {
-      ty
-    }
-  }
-
-  fn bare_type_check(exprssion, expected_type) -> Ty { ... }
- */
-
-// from https://www.youtube.com/watch?v=il3gD7XMdmA
-// typeInfer :: Expr a -> Matching (Type a)
-// unify :: Type a -> Type b -> Matching (Type c)
-
-impl TypeContext {
-  pub fn type_check(&mut self, ast: &AST) -> TypeCheckResult {
-    let mut last = TypeVariable::Univ(UVar::Unit);
-    for statement in ast.0.iter() {
-      match statement {
-        &Statement::Declaration(ref _decl) => {
-          //return Err(format!("Declarations not supported"));
-        },
-        &Statement::ExpressionStatement(ref expr) => {
-          last = self.infer(expr)?;
-        }
-      }
-    }
-    Ok(last)
-  }
-
-  fn infer(&mut self, expr: &Expression) -> TypeCheckResult {
-    use self::ExpressionType::*;
-    use self::TypeVariable::*;
-
-    Ok(match (&expr.0, &expr.1) {
-      (ref _t, &Some(ref anno)) => {
-        //TODO make this better,
-        self.from_anno(anno)
-      },
-      (&IntLiteral(_), _) => Univ(UVar::Integer),
-      (&FloatLiteral(_), _) => Univ(UVar::Float),
-      (&BoolLiteral(_), _) => Univ(UVar::Boolean),
-      (&Variable(ref name), _) => self.lookup(name).map(|entry| entry.type_var)
-        .ok_or(format!("Couldn't find {}", name))?,
-      (&BinExp(ref op, box ref lhs, box ref rhs), _) => {
-        let _f_type = self.infer_op(op);
-        let _lhs_type = self.infer(&lhs);
-        let _rhs_type = self.infer(&rhs);
-        unimplemented!()
-      },
-      (&Call { ref f, ref arguments }, _) => {
-        let f_type = self.infer(&*f)?;
-        let arg_type = self.infer(arguments.get(0).unwrap())?; // TODO fix later
-        match f_type {
-          Univ(UVar::Function(box t1, box ret_type)) => {
-            let _ = self.unify(&t1, &arg_type)?;
-            ret_type
-          },
-          _ => return Err(format!("Type error"))
-        }
-      },
-      _ => Univ(UVar::Unit),
-    })
-  }
-
-  fn infer_op(&mut self, _op: &Operation) -> TypeCheckResult {
-    use self::TypeVariable::*;
-    Ok(
-      Univ(UVar::Function(
-        Box::new(Univ(UVar::Integer)),
-        Box::new(Univ(UVar::Function(
-          Box::new(Univ(UVar::Integer)),
-          Box::new(Univ(UVar::Integer))
-          )))
-        ))
-      )
-  }
-
-  fn unify(&mut self, t1: &TypeVariable, t2: &TypeVariable) -> TypeCheckResult {
-    if t1 == t2 {
-      Ok(t1.clone())
-    } else {
-      Err(format!("Types {:?} and {:?} don't unify", t1, t2))
-    }
-  }
-}
-

src/webapp.rs

@@ -1,36 +0,0 @@
-use rocket;
-use rocket::response::NamedFile;
-use rocket_contrib::Json;
-use schala_lang;
-use language::{ProgrammingLanguageInterface, EvalOptions};
-
-#[get("/")]
-fn index() -> Result<NamedFile, ()> {
-  NamedFile::open("static/index.html").map_err(|_| ())
-}
-
-#[get("/bundle.js")]
-fn js_bundle() -> Result<NamedFile, ()> {
-  NamedFile::open("static/bundle.js").map_err(|_| ())
-}
-
-#[derive(Debug, Serialize, Deserialize)]
-struct Input {
-  source: String,
-}
-
-#[derive(Serialize, Deserialize)]
-struct Output {
-  text: String,
-}
-
-#[post("/input", format = "application/json", data = "<input>")]
-fn interpreter_input(input: Json<Input>) -> Json<Output> {
-  let mut schala = schala_lang::Schala::new();
-  let code_output = schala.evaluate_in_repl(&input.source, &EvalOptions::default());
-  Json(Output { text: code_output.to_string() })
-}
-
-pub fn web_main() {
-  rocket::ignite().mount("/", routes![index, js_bundle, interpreter_input]).launch();
-}

static/main.jsx

@@ -1,6 +1,6 @@
 const React = require("react");
 const ReactDOM = require("react-dom");
-const request = require("request");
+const superagent = require("superagent");
 
 const serverAddress = "http://localhost:8000";
 
@@ -20,14 +20,17 @@ class CodeArea extends React.Component {
     console.log("Event", this.state.value);
     const source = this.state.value;
 
-    const options = {
-      url: `${serverAddress}/input`,
-      json: true,
-      body: { source }
-    };
-    request.post(options, (error, response, body) => {
-      this.setState({lastOutput: body.text})
-    });
+    superagent.post(`${serverAddress}/input`)
+      .send({ source })
+      .set("accept", "json")
+      .end((error, response) => {
+        if (response) {
+          console.log("Resp", response);
+          this.setState({lastOutput: response.body.text})
+        } else {
+          console.error("Error: ", error);
+        }
+      });
   }
 
   renderOutput() {

static/package.json

@@ -11,7 +11,7 @@
     "browserify": "^14.4.0",
     "react": "^15.6.1",
     "react-dom": "^15.6.1",
-    "request": "^2.82.0",
+    "superagent": "^3.6.3",
     "uglify-js": "^3.1.1"
   },
   "babel": {

static/yarn.lock

@@ -13,15 +13,6 @@ acorn@^4.0.3:
   version "4.0.13"
   resolved "https://registry.yarnpkg.com/acorn/-/acorn-4.0.13.tgz#105495ae5361d697bd195c825192e1ad7f253787"
 
-ajv@^5.1.0:
-  version "5.2.2"
-  resolved "https://registry.yarnpkg.com/ajv/-/ajv-5.2.2.tgz#47c68d69e86f5d953103b0074a9430dc63da5e39"
-  dependencies:
-    co "^4.6.0"
-    fast-deep-equal "^1.0.0"
-    json-schema-traverse "^0.3.0"
-    json-stable-stringify "^1.0.1"
-
 ansi-regex@^2.0.0:
   version "2.1.1"
   resolved "https://registry.yarnpkg.com/ansi-regex/-/ansi-regex-2.1.1.tgz#c3b33ab5ee360d86e0e628f0468ae7ef27d654df"
@@ -54,14 +45,6 @@ asn1.js@^4.0.0:
     inherits "^2.0.1"
     minimalistic-assert "^1.0.0"
 
-asn1@~0.2.3:
-  version "0.2.3"
-  resolved "https://registry.yarnpkg.com/asn1/-/asn1-0.2.3.tgz#dac8787713c9966849fc8180777ebe9c1ddf3b86"
-
-assert-plus@1.0.0, assert-plus@^1.0.0:
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/assert-plus/-/assert-plus-1.0.0.tgz#f12e0f3c5d77b0b1cdd9146942e4e96c1e4dd525"
-
 assert@^1.4.0:
   version "1.4.1"
   resolved "https://registry.yarnpkg.com/assert/-/assert-1.4.1.tgz#99912d591836b5a6f5b345c0f07eefc08fc65d91"
@@ -78,14 +61,6 @@ asynckit@^0.4.0:
   version "0.4.0"
   resolved "https://registry.yarnpkg.com/asynckit/-/asynckit-0.4.0.tgz#c79ed97f7f34cb8f2ba1bc9790bcc366474b4b79"
 
-aws-sign2@~0.7.0:
-  version "0.7.0"
-  resolved "https://registry.yarnpkg.com/aws-sign2/-/aws-sign2-0.7.0.tgz#b46e890934a9591f2d2f6f86d7e6a9f1b3fe76a8"
-
-aws4@^1.6.0:
-  version "1.6.0"
-  resolved "https://registry.yarnpkg.com/aws4/-/aws4-1.6.0.tgz#83ef5ca860b2b32e4a0deedee8c771b9db57471e"
-
 babel-code-frame@^6.26.0:
   version "6.26.0"
   resolved "https://registry.yarnpkg.com/babel-code-frame/-/babel-code-frame-6.26.0.tgz#63fd43f7dc1e3bb7ce35947db8fe369a3f58c74b"
@@ -571,28 +546,10 @@ base64-js@^1.0.2:
   version "1.2.1"
   resolved "https://registry.yarnpkg.com/base64-js/-/base64-js-1.2.1.tgz#a91947da1f4a516ea38e5b4ec0ec3773675e0886"
 
-bcrypt-pbkdf@^1.0.0:
-  version "1.0.1"
-  resolved "https://registry.yarnpkg.com/bcrypt-pbkdf/-/bcrypt-pbkdf-1.0.1.tgz#63bc5dcb61331b92bc05fd528953c33462a06f8d"
-  dependencies:
-    tweetnacl "^0.14.3"
-
 bn.js@^4.0.0, bn.js@^4.1.0, bn.js@^4.1.1, bn.js@^4.4.0:
   version "4.11.8"
   resolved "https://registry.yarnpkg.com/bn.js/-/bn.js-4.11.8.tgz#2cde09eb5ee341f484746bb0309b3253b1b1442f"
 
-boom@4.x.x:
-  version "4.3.1"
-  resolved "https://registry.yarnpkg.com/boom/-/boom-4.3.1.tgz#4f8a3005cb4a7e3889f749030fd25b96e01d2e31"
-  dependencies:
-    hoek "4.x.x"
-
-boom@5.x.x:
-  version "5.2.0"
-  resolved "https://registry.yarnpkg.com/boom/-/boom-5.2.0.tgz#5dd9da6ee3a5f302077436290cb717d3f4a54e02"
-  dependencies:
-    hoek "4.x.x"
-
 brace-expansion@^1.1.7:
   version "1.1.8"
   resolved "https://registry.yarnpkg.com/brace-expansion/-/brace-expansion-1.1.8.tgz#c07b211c7c952ec1f8efd51a77ef0d1d3990a292"
@@ -743,10 +700,6 @@ cached-path-relative@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/cached-path-relative/-/cached-path-relative-1.0.1.tgz#d09c4b52800aa4c078e2dd81a869aac90d2e54e7"
 
-caseless@~0.12.0:
-  version "0.12.0"
-  resolved "https://registry.yarnpkg.com/caseless/-/caseless-0.12.0.tgz#1b681c21ff84033c826543090689420d187151dc"
-
 chalk@^1.1.3:
   version "1.1.3"
   resolved "https://registry.yarnpkg.com/chalk/-/chalk-1.1.3.tgz#a8115c55e4a702fe4d150abd3872822a7e09fc98"
@@ -764,10 +717,6 @@ cipher-base@^1.0.0, cipher-base@^1.0.1, cipher-base@^1.0.3:
     inherits "^2.0.1"
     safe-buffer "^5.0.1"
 
-co@^4.6.0:
-  version "4.6.0"
-  resolved "https://registry.yarnpkg.com/co/-/co-4.6.0.tgz#6ea6bdf3d853ae54ccb8e47bfa0bf3f9031fb184"
-
 combine-source-map@~0.7.1:
   version "0.7.2"
   resolved "https://registry.yarnpkg.com/combine-source-map/-/combine-source-map-0.7.2.tgz#0870312856b307a87cc4ac486f3a9a62aeccc09e"
@@ -777,7 +726,7 @@ combine-source-map@~0.7.1:
     lodash.memoize "~3.0.3"
     source-map "~0.5.3"
 
-combined-stream@^1.0.5, combined-stream@~1.0.5:
+combined-stream@^1.0.5:
   version "1.0.5"
   resolved "https://registry.yarnpkg.com/combined-stream/-/combined-stream-1.0.5.tgz#938370a57b4a51dea2c77c15d5c5fdf895164009"
   dependencies:
@@ -787,6 +736,10 @@ commander@~2.11.0:
   version "2.11.0"
   resolved "https://registry.yarnpkg.com/commander/-/commander-2.11.0.tgz#157152fd1e7a6c8d98a5b715cf376df928004563"
 
+component-emitter@^1.2.0:
+  version "1.2.1"
+  resolved "https://registry.yarnpkg.com/component-emitter/-/component-emitter-1.2.1.tgz#137918d6d78283f7df7a6b7c5a63e140e69425e6"
+
 concat-map@0.0.1:
   version "0.0.1"
   resolved "https://registry.yarnpkg.com/concat-map/-/concat-map-0.0.1.tgz#d8a96bd77fd68df7793a73036a3ba0d5405d477b"
@@ -817,6 +770,10 @@ convert-source-map@~1.1.0:
   version "1.1.3"
   resolved "https://registry.yarnpkg.com/convert-source-map/-/convert-source-map-1.1.3.tgz#4829c877e9fe49b3161f3bf3673888e204699860"
 
+cookiejar@^2.1.0:
+  version "2.1.1"
+  resolved "https://registry.yarnpkg.com/cookiejar/-/cookiejar-2.1.1.tgz#41ad57b1b555951ec171412a81942b1e8200d34a"
+
 core-js@^1.0.0:
   version "1.2.7"
   resolved "https://registry.yarnpkg.com/core-js/-/core-js-1.2.7.tgz#652294c14651db28fa93bd2d5ff2983a4f08c636"
@@ -825,7 +782,7 @@ core-js@^2.4.0, core-js@^2.5.0:
   version "2.5.1"
   resolved "https://registry.yarnpkg.com/core-js/-/core-js-2.5.1.tgz#ae6874dc66937789b80754ff5428df66819ca50b"
 
-core-util-is@1.0.2, core-util-is@~1.0.0:
+core-util-is@~1.0.0:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/core-util-is/-/core-util-is-1.0.2.tgz#b5fd54220aa2bc5ab57aab7140c940754503c1a7"
 
@@ -864,12 +821,6 @@ create-react-class@^15.6.0:
     loose-envify "^1.3.1"
     object-assign "^4.1.1"
 
-cryptiles@3.x.x:
-  version "3.1.2"
-  resolved "https://registry.yarnpkg.com/cryptiles/-/cryptiles-3.1.2.tgz#a89fbb220f5ce25ec56e8c4aa8a4fd7b5b0d29fe"
-  dependencies:
-    boom "5.x.x"
-
 crypto-browserify@^3.0.0:
   version "3.11.1"
   resolved "https://registry.yarnpkg.com/crypto-browserify/-/crypto-browserify-3.11.1.tgz#948945efc6757a400d6e5e5af47194d10064279f"
@@ -885,12 +836,6 @@ crypto-browserify@^3.0.0:
     public-encrypt "^4.0.0"
     randombytes "^2.0.0"
 
-dashdash@^1.12.0:
-  version "1.14.1"
-  resolved "https://registry.yarnpkg.com/dashdash/-/dashdash-1.14.1.tgz#853cfa0f7cbe2fed5de20326b8dd581035f6e2f0"
-  dependencies:
-    assert-plus "^1.0.0"
-
 date-now@^0.1.4:
   version "0.1.4"
   resolved "https://registry.yarnpkg.com/date-now/-/date-now-0.1.4.tgz#eaf439fd4d4848ad74e5cc7dbef200672b9e345b"
@@ -901,6 +846,12 @@ debug@^2.6.8:
   dependencies:
     ms "2.0.0"
 
+debug@^3.1.0:
+  version "3.1.0"
+  resolved "https://registry.yarnpkg.com/debug/-/debug-3.1.0.tgz#5bb5a0672628b64149566ba16819e61518c67261"
+  dependencies:
+    ms "2.0.0"
+
 defined@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/defined/-/defined-1.0.0.tgz#c98d9bcef75674188e110969151199e39b1fa693"
@@ -956,12 +907,6 @@ duplexer2@^0.1.2, duplexer2@~0.1.0, duplexer2@~0.1.2:
   dependencies:
     readable-stream "^2.0.2"
 
-ecc-jsbn@~0.1.1:
-  version "0.1.1"
-  resolved "https://registry.yarnpkg.com/ecc-jsbn/-/ecc-jsbn-0.1.1.tgz#0fc73a9ed5f0d53c38193398523ef7e543777505"
-  dependencies:
-    jsbn "~0.1.0"
-
 elliptic@^6.0.0:
   version "6.4.0"
   resolved "https://registry.yarnpkg.com/elliptic/-/elliptic-6.4.0.tgz#cac9af8762c85836187003c8dfe193e5e2eae5df"
@@ -999,18 +944,10 @@ evp_bytestokey@^1.0.0, evp_bytestokey@^1.0.3:
     md5.js "^1.3.4"
     safe-buffer "^5.1.1"
 
-extend@~3.0.1:
+extend@^3.0.0:
   version "3.0.1"
   resolved "https://registry.yarnpkg.com/extend/-/extend-3.0.1.tgz#a755ea7bc1adfcc5a31ce7e762dbaadc5e636444"
 
-extsprintf@1.3.0, extsprintf@^1.2.0:
-  version "1.3.0"
-  resolved "https://registry.yarnpkg.com/extsprintf/-/extsprintf-1.3.0.tgz#96918440e3041a7a414f8c52e3c574eb3c3e1e05"
-
-fast-deep-equal@^1.0.0:
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/fast-deep-equal/-/fast-deep-equal-1.0.0.tgz#96256a3bc975595eb36d82e9929d060d893439ff"
-
 fbjs@^0.8.9:
   version "0.8.15"
   resolved "https://registry.yarnpkg.com/fbjs/-/fbjs-0.8.15.tgz#4f0695fdfcc16c37c0b07facec8cb4c4091685b9"
@@ -1023,11 +960,7 @@ fbjs@^0.8.9:
     setimmediate "^1.0.5"
     ua-parser-js "^0.7.9"
 
-forever-agent@~0.6.1:
-  version "0.6.1"
-  resolved "https://registry.yarnpkg.com/forever-agent/-/forever-agent-0.6.1.tgz#fbc71f0c41adeb37f96c577ad1ed42d8fdacca91"
-
-form-data@~2.3.1:
+form-data@^2.3.1:
   version "2.3.1"
   resolved "https://registry.yarnpkg.com/form-data/-/form-data-2.3.1.tgz#6fb94fbd71885306d73d15cc497fe4cc4ecd44bf"
   dependencies:
@@ -1035,6 +968,10 @@ form-data@~2.3.1:
     combined-stream "^1.0.5"
     mime-types "^2.1.12"
 
+formidable@^1.1.1:
+  version "1.1.1"
+  resolved "https://registry.yarnpkg.com/formidable/-/formidable-1.1.1.tgz#96b8886f7c3c3508b932d6bd70c4d3a88f35f1a9"
+
 fs.realpath@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/fs.realpath/-/fs.realpath-1.0.0.tgz#1504ad2523158caa40db4a2787cb01411994ea4f"
@@ -1043,12 +980,6 @@ function-bind@^1.0.2:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/function-bind/-/function-bind-1.1.1.tgz#a56899d3ea3c9bab874bb9773b7c5ede92f4895d"
 
-getpass@^0.1.1:
-  version "0.1.7"
-  resolved "https://registry.yarnpkg.com/getpass/-/getpass-0.1.7.tgz#5eff8e3e684d569ae4cb2b1282604e8ba62149fa"
-  dependencies:
-    assert-plus "^1.0.0"
-
 glob@^7.1.0:
   version "7.1.2"
   resolved "https://registry.yarnpkg.com/glob/-/glob-7.1.2.tgz#c19c9df9a028702d678612384a6552404c636d15"
@@ -1064,17 +995,6 @@ globals@^9.18.0:
   version "9.18.0"
   resolved "https://registry.yarnpkg.com/globals/-/globals-9.18.0.tgz#aa3896b3e69b487f17e31ed2143d69a8e30c2d8a"
 
-har-schema@^2.0.0:
-  version "2.0.0"
-  resolved "https://registry.yarnpkg.com/har-schema/-/har-schema-2.0.0.tgz#a94c2224ebcac04782a0d9035521f24735b7ec92"
-
-har-validator@~5.0.3:
-  version "5.0.3"
-  resolved "https://registry.yarnpkg.com/har-validator/-/har-validator-5.0.3.tgz#ba402c266194f15956ef15e0fcf242993f6a7dfd"
-  dependencies:
-    ajv "^5.1.0"
-    har-schema "^2.0.0"
-
 has-ansi@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/has-ansi/-/has-ansi-2.0.0.tgz#34f5049ce1ecdf2b0649af3ef24e45ed35416d91"
@@ -1107,15 +1027,6 @@ hash.js@^1.0.0, hash.js@^1.0.3:
     inherits "^2.0.3"
     minimalistic-assert "^1.0.0"
 
-hawk@~6.0.2:
-  version "6.0.2"
-  resolved "https://registry.yarnpkg.com/hawk/-/hawk-6.0.2.tgz#af4d914eb065f9b5ce4d9d11c1cb2126eecc3038"
-  dependencies:
-    boom "4.x.x"
-    cryptiles "3.x.x"
-    hoek "4.x.x"
-    sntp "2.x.x"
-
 hmac-drbg@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/hmac-drbg/-/hmac-drbg-1.0.1.tgz#d2745701025a6c775a6c545793ed502fc0c649a1"
@@ -1124,10 +1035,6 @@ hmac-drbg@^1.0.0:
     minimalistic-assert "^1.0.0"
     minimalistic-crypto-utils "^1.0.1"
 
-hoek@4.x.x:
-  version "4.2.0"
-  resolved "https://registry.yarnpkg.com/hoek/-/hoek-4.2.0.tgz#72d9d0754f7fe25ca2d01ad8f8f9a9449a89526d"
-
 home-or-tmp@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/home-or-tmp/-/home-or-tmp-2.0.0.tgz#e36c3f2d2cae7d746a857e38d18d5f32a7882db8"
@@ -1139,14 +1046,6 @@ htmlescape@^1.1.0:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/htmlescape/-/htmlescape-1.1.1.tgz#3a03edc2214bca3b66424a3e7959349509cb0351"
 
-http-signature@~1.2.0:
-  version "1.2.0"
-  resolved "https://registry.yarnpkg.com/http-signature/-/http-signature-1.2.0.tgz#9aecd925114772f3d95b65a60abb8f7c18fbace1"
-  dependencies:
-    assert-plus "^1.0.0"
-    jsprim "^1.2.2"
-    sshpk "^1.7.0"
-
 https-browserify@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/https-browserify/-/https-browserify-1.0.0.tgz#ec06c10e0a34c0f2faf199f7fd7fc78fffd03c73"
@@ -1217,10 +1116,6 @@ is-stream@^1.0.1:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/is-stream/-/is-stream-1.1.0.tgz#12d4a3dd4e68e0b79ceb8dbc84173ae80d91ca44"
 
-is-typedarray@~1.0.0:
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/is-typedarray/-/is-typedarray-1.0.0.tgz#e479c80858df0c1b11ddda6940f96011fcda4a9a"
-
 isarray@~0.0.1:
   version "0.0.1"
   resolved "https://registry.yarnpkg.com/isarray/-/isarray-0.0.1.tgz#8a18acfca9a8f4177e09abfc6038939b05d1eedf"
@@ -1236,18 +1131,10 @@ isomorphic-fetch@^2.1.1:
     node-fetch "^1.0.1"
     whatwg-fetch ">=0.10.0"
 
-isstream@~0.1.2:
-  version "0.1.2"
-  resolved "https://registry.yarnpkg.com/isstream/-/isstream-0.1.2.tgz#47e63f7af55afa6f92e1500e690eb8b8529c099a"
-
 js-tokens@^3.0.0, js-tokens@^3.0.2:
   version "3.0.2"
   resolved "https://registry.yarnpkg.com/js-tokens/-/js-tokens-3.0.2.tgz#9866df395102130e38f7f996bceb65443209c25b"
 
-jsbn@~0.1.0:
-  version "0.1.1"
-  resolved "https://registry.yarnpkg.com/jsbn/-/jsbn-0.1.1.tgz#a5e654c2e5a2deb5f201d96cefbca80c0ef2f513"
-
 jsesc@^1.3.0:
   version "1.3.0"
   resolved "https://registry.yarnpkg.com/jsesc/-/jsesc-1.3.0.tgz#46c3fec8c1892b12b0833db9bc7622176dbab34b"
@@ -1256,30 +1143,12 @@ jsesc@~0.5.0:
   version "0.5.0"
   resolved "https://registry.yarnpkg.com/jsesc/-/jsesc-0.5.0.tgz#e7dee66e35d6fc16f710fe91d5cf69f70f08911d"
 
-json-schema-traverse@^0.3.0:
-  version "0.3.1"
-  resolved "https://registry.yarnpkg.com/json-schema-traverse/-/json-schema-traverse-0.3.1.tgz#349a6d44c53a51de89b40805c5d5e59b417d3340"
-
-json-schema@0.2.3:
-  version "0.2.3"
-  resolved "https://registry.yarnpkg.com/json-schema/-/json-schema-0.2.3.tgz#b480c892e59a2f05954ce727bd3f2a4e882f9e13"
-
-json-stable-stringify@^1.0.1:
-  version "1.0.1"
-  resolved "https://registry.yarnpkg.com/json-stable-stringify/-/json-stable-stringify-1.0.1.tgz#9a759d39c5f2ff503fd5300646ed445f88c4f9af"
-  dependencies:
-    jsonify "~0.0.0"
-
 json-stable-stringify@~0.0.0:
   version "0.0.1"
   resolved "https://registry.yarnpkg.com/json-stable-stringify/-/json-stable-stringify-0.0.1.tgz#611c23e814db375527df851193db59dd2af27f45"
   dependencies:
     jsonify "~0.0.0"
 
-json-stringify-safe@~5.0.1:
-  version "5.0.1"
-  resolved "https://registry.yarnpkg.com/json-stringify-safe/-/json-stringify-safe-5.0.1.tgz#1296a2d58fd45f19a0f6ce01d65701e2c735b6eb"
-
 json5@^0.5.1:
   version "0.5.1"
   resolved "https://registry.yarnpkg.com/json5/-/json5-0.5.1.tgz#1eade7acc012034ad84e2396767ead9fa5495821"
@@ -1292,15 +1161,6 @@ jsonparse@^1.2.0:
   version "1.3.1"
   resolved "https://registry.yarnpkg.com/jsonparse/-/jsonparse-1.3.1.tgz#3f4dae4a91fac315f71062f8521cc239f1366280"
 
-jsprim@^1.2.2:
-  version "1.4.1"
-  resolved "https://registry.yarnpkg.com/jsprim/-/jsprim-1.4.1.tgz#313e66bc1e5cc06e438bc1b7499c2e5c56acb6a2"
-  dependencies:
-    assert-plus "1.0.0"
-    extsprintf "1.3.0"
-    json-schema "0.2.3"
-    verror "1.10.0"
-
 labeled-stream-splicer@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/labeled-stream-splicer/-/labeled-stream-splicer-2.0.0.tgz#a52e1d138024c00b86b1c0c91f677918b8ae0a59"
@@ -1336,6 +1196,10 @@ md5.js@^1.3.4:
     hash-base "^3.0.0"
     inherits "^2.0.1"
 
+methods@^1.1.1:
+  version "1.1.2"
+  resolved "https://registry.yarnpkg.com/methods/-/methods-1.1.2.tgz#5529a4d67654134edcc5266656835b0f851afcee"
+
 miller-rabin@^4.0.0:
   version "4.0.0"
   resolved "https://registry.yarnpkg.com/miller-rabin/-/miller-rabin-4.0.0.tgz#4a62fb1d42933c05583982f4c716f6fb9e6c6d3d"
@@ -1347,12 +1211,16 @@ mime-db@~1.30.0:
   version "1.30.0"
   resolved "https://registry.yarnpkg.com/mime-db/-/mime-db-1.30.0.tgz#74c643da2dd9d6a45399963465b26d5ca7d71f01"
 
-mime-types@^2.1.12, mime-types@~2.1.17:
+mime-types@^2.1.12:
   version "2.1.17"
   resolved "https://registry.yarnpkg.com/mime-types/-/mime-types-2.1.17.tgz#09d7a393f03e995a79f8af857b70a9e0ab16557a"
   dependencies:
     mime-db "~1.30.0"
 
+mime@^1.4.1:
+  version "1.4.1"
+  resolved "https://registry.yarnpkg.com/mime/-/mime-1.4.1.tgz#121f9ebc49e3766f311a76e1fa1c8003c4b03aa6"
+
 minimalistic-assert@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/minimalistic-assert/-/minimalistic-assert-1.0.0.tgz#702be2dda6b37f4836bcb3f5db56641b64a1d3d3"
@@ -1416,10 +1284,6 @@ number-is-nan@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/number-is-nan/-/number-is-nan-1.0.1.tgz#097b602b53422a522c1afb8790318336941a011d"
 
-oauth-sign@~0.8.2:
-  version "0.8.2"
-  resolved "https://registry.yarnpkg.com/oauth-sign/-/oauth-sign-0.8.2.tgz#46a6ab7f0aead8deae9ec0565780b7d4efeb9d43"
-
 object-assign@^4.0.0, object-assign@^4.1.0, object-assign@^4.1.1:
   version "4.1.1"
   resolved "https://registry.yarnpkg.com/object-assign/-/object-assign-4.1.1.tgz#2109adc7965887cfc05cbbd442cac8bfbb360863"
@@ -1488,10 +1352,6 @@ pbkdf2@^3.0.3:
     safe-buffer "^5.0.1"
     sha.js "^2.4.8"
 
-performance-now@^2.1.0:
-  version "2.1.0"
-  resolved "https://registry.yarnpkg.com/performance-now/-/performance-now-2.1.0.tgz#6309f4e0e5fa913ec1c69307ae364b4b377c9e7b"
-
 private@^0.1.6, private@^0.1.7:
   version "0.1.7"
   resolved "https://registry.yarnpkg.com/private/-/private-0.1.7.tgz#68ce5e8a1ef0a23bb570cc28537b5332aba63ef1"
@@ -1531,11 +1391,11 @@ punycode@1.3.2:
   version "1.3.2"
   resolved "https://registry.yarnpkg.com/punycode/-/punycode-1.3.2.tgz#9653a036fb7c1ee42342f2325cceefea3926c48d"
 
-punycode@^1.3.2, punycode@^1.4.1:
+punycode@^1.3.2:
   version "1.4.1"
   resolved "https://registry.yarnpkg.com/punycode/-/punycode-1.4.1.tgz#c0d5a63b2718800ad8e1eb0fa5269c84dd41845e"
 
-qs@~6.5.1:
+qs@^6.5.1:
   version "6.5.1"
   resolved "https://registry.yarnpkg.com/qs/-/qs-6.5.1.tgz#349cdf6eef89ec45c12d7d5eb3fc0c870343a6d8"
 
@@ -1578,7 +1438,7 @@ read-only-stream@^2.0.0:
   dependencies:
     readable-stream "^2.0.2"
 
-readable-stream@^2.0.2, readable-stream@^2.1.5, readable-stream@^2.2.6:
+readable-stream@^2.0.2, readable-stream@^2.0.5, readable-stream@^2.1.5, readable-stream@^2.2.6:
   version "2.3.3"
   resolved "https://registry.yarnpkg.com/readable-stream/-/readable-stream-2.3.3.tgz#368f2512d79f9d46fdfc71349ae7878bbc1eb95c"
   dependencies:
@@ -1641,33 +1501,6 @@ repeating@^2.0.0:
   dependencies:
     is-finite "^1.0.0"
 
-request@^2.82.0:
-  version "2.82.0"
-  resolved "https://registry.yarnpkg.com/request/-/request-2.82.0.tgz#2ba8a92cd7ac45660ea2b10a53ae67cd247516ea"
-  dependencies:
-    aws-sign2 "~0.7.0"
-    aws4 "^1.6.0"
-    caseless "~0.12.0"
-    combined-stream "~1.0.5"
-    extend "~3.0.1"
-    forever-agent "~0.6.1"
-    form-data "~2.3.1"
-    har-validator "~5.0.3"
-    hawk "~6.0.2"
-    http-signature "~1.2.0"
-    is-typedarray "~1.0.0"
-    isstream "~0.1.2"
-    json-stringify-safe "~5.0.1"
-    mime-types "~2.1.17"
-    oauth-sign "~0.8.2"
-    performance-now "^2.1.0"
-    qs "~6.5.1"
-    safe-buffer "^5.1.1"
-    stringstream "~0.0.5"
-    tough-cookie "~2.3.2"
-    tunnel-agent "^0.6.0"
-    uuid "^3.1.0"
-
 resolve@1.1.7:
   version "1.1.7"
   resolved "https://registry.yarnpkg.com/resolve/-/resolve-1.1.7.tgz#203114d82ad2c5ed9e8e0411b3932875e889e97b"
@@ -1719,12 +1552,6 @@ slash@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/slash/-/slash-1.0.0.tgz#c41f2f6c39fc16d1cd17ad4b5d896114ae470d55"
 
-sntp@2.x.x:
-  version "2.0.2"
-  resolved "https://registry.yarnpkg.com/sntp/-/sntp-2.0.2.tgz#5064110f0af85f7cfdb7d6b67a40028ce52b4b2b"
-  dependencies:
-    hoek "4.x.x"
-
 source-map-support@^0.4.15:
   version "0.4.18"
   resolved "https://registry.yarnpkg.com/source-map-support/-/source-map-support-0.4.18.tgz#0286a6de8be42641338594e97ccea75f0a2c585f"
@@ -1735,20 +1562,6 @@ source-map@^0.5.6, source-map@~0.5.1, source-map@~0.5.3:
   version "0.5.7"
   resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.5.7.tgz#8a039d2d1021d22d1ea14c80d8ea468ba2ef3fcc"
 
-sshpk@^1.7.0:
-  version "1.13.1"
-  resolved "https://registry.yarnpkg.com/sshpk/-/sshpk-1.13.1.tgz#512df6da6287144316dc4c18fe1cf1d940739be3"
-  dependencies:
-    asn1 "~0.2.3"
-    assert-plus "^1.0.0"
-    dashdash "^1.12.0"
-    getpass "^0.1.1"
-  optionalDependencies:
-    bcrypt-pbkdf "^1.0.0"
-    ecc-jsbn "~0.1.1"
-    jsbn "~0.1.0"
-    tweetnacl "~0.14.0"
-
 stream-browserify@^2.0.0:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/stream-browserify/-/stream-browserify-2.0.1.tgz#66266ee5f9bdb9940a4e4514cafb43bb71e5c9db"
@@ -1790,10 +1603,6 @@ string_decoder@~1.0.0, string_decoder@~1.0.3:
   dependencies:
     safe-buffer "~5.1.0"
 
-stringstream@~0.0.5:
-  version "0.0.5"
-  resolved "https://registry.yarnpkg.com/stringstream/-/stringstream-0.0.5.tgz#4e484cd4de5a0bbbee18e46307710a8a81621878"
-
 strip-ansi@^3.0.0:
   version "3.0.1"
   resolved "https://registry.yarnpkg.com/strip-ansi/-/strip-ansi-3.0.1.tgz#6a385fb8853d952d5ff05d0e8aaf94278dc63dcf"
@@ -1806,6 +1615,21 @@ subarg@^1.0.0:
   dependencies:
     minimist "^1.1.0"
 
+superagent@^3.6.3:
+  version "3.6.3"
+  resolved "https://registry.yarnpkg.com/superagent/-/superagent-3.6.3.tgz#eb95fcb576a9d23a730a9d0789731b5379a36cdc"
+  dependencies:
+    component-emitter "^1.2.0"
+    cookiejar "^2.1.0"
+    debug "^3.1.0"
+    extend "^3.0.0"
+    form-data "^2.3.1"
+    formidable "^1.1.1"
+    methods "^1.1.1"
+    mime "^1.4.1"
+    qs "^6.5.1"
+    readable-stream "^2.0.5"
+
 supports-color@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/supports-color/-/supports-color-2.0.0.tgz#535d045ce6b6363fa40117084629995e9df324c7"
@@ -1841,12 +1665,6 @@ to-fast-properties@^1.0.3:
   version "1.0.3"
   resolved "https://registry.yarnpkg.com/to-fast-properties/-/to-fast-properties-1.0.3.tgz#b83571fa4d8c25b82e231b06e3a3055de4ca1a47"
 
-tough-cookie@~2.3.2:
-  version "2.3.2"
-  resolved "https://registry.yarnpkg.com/tough-cookie/-/tough-cookie-2.3.2.tgz#f081f76e4c85720e6c37a5faced737150d84072a"
-  dependencies:
-    punycode "^1.4.1"
-
 trim-right@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/trim-right/-/trim-right-1.0.1.tgz#cb2e1203067e0c8de1f614094b9fe45704ea6003"
@@ -1855,16 +1673,6 @@ tty-browserify@~0.0.0:
   version "0.0.0"
   resolved "https://registry.yarnpkg.com/tty-browserify/-/tty-browserify-0.0.0.tgz#a157ba402da24e9bf957f9aa69d524eed42901a6"
 
-tunnel-agent@^0.6.0:
-  version "0.6.0"
-  resolved "https://registry.yarnpkg.com/tunnel-agent/-/tunnel-agent-0.6.0.tgz#27a5dea06b36b04a0a9966774b290868f0fc40fd"
-  dependencies:
-    safe-buffer "^5.0.1"
-
-tweetnacl@^0.14.3, tweetnacl@~0.14.0:
-  version "0.14.5"
-  resolved "https://registry.yarnpkg.com/tweetnacl/-/tweetnacl-0.14.5.tgz#5ae68177f192d4456269d108afa93ff8743f4f64"
-
 typedarray@~0.0.5:
   version "0.0.6"
   resolved "https://registry.yarnpkg.com/typedarray/-/typedarray-0.0.6.tgz#867ac74e3864187b1d3d47d996a78ec5c8830777"
@@ -1901,18 +1709,6 @@ util@0.10.3, util@~0.10.1:
   dependencies:
     inherits "2.0.1"
 
-uuid@^3.1.0:
-  version "3.1.0"
-  resolved "https://registry.yarnpkg.com/uuid/-/uuid-3.1.0.tgz#3dd3d3e790abc24d7b0d3a034ffababe28ebbc04"
-
-verror@1.10.0:
-  version "1.10.0"
-  resolved "https://registry.yarnpkg.com/verror/-/verror-1.10.0.tgz#3a105ca17053af55d6e270c1f8288682e18da400"
-  dependencies:
-    assert-plus "^1.0.0"
-    core-util-is "1.0.2"
-    extsprintf "^1.2.0"
-
 vm-browserify@~0.0.1:
   version "0.0.4"
   resolved "https://registry.yarnpkg.com/vm-browserify/-/vm-browserify-0.0.4.tgz#5d7ea45bbef9e4a6ff65f95438e0a87c357d5a73"