diff --git a/schala-lang/language/src/tree_walk_eval/mod.rs b/schala-lang/language/src/tree_walk_eval/mod.rs
index cb8c899..29a3fde 100644
--- a/schala-lang/language/src/tree_walk_eval/mod.rs
+++ b/schala-lang/language/src/tree_walk_eval/mod.rs
@@ -78,6 +78,8 @@ fn paren_wrapped(terms: impl Iterator<Item=String>) -> String {
   buf
 }
 
+/// Anything that can be stored in memory; that is, a function definition, or a fully-evaluated
+/// program value.
 #[derive(Debug)]
 enum MemoryValue {
     Function(FunctionDefinition),
@@ -90,33 +92,6 @@ impl From<Primitive> for MemoryValue {
     }
 }
 
-fn expr_to_repl(expr: &Expression) -> String {
-    match expr {
-        Expression::Literal(lit) => match lit {
-            Literal::Nat(n) => format!("{}", n),
-            Literal::Int(i) => format!("{}", i),
-            Literal::Float(f) => format!("{}", f),
-            Literal::Bool(b) => format!("{}", b),
-            Literal::StringLit(s) => format!("\"{}\"", s),
-        }
-        Expression::Tuple(terms) => paren_wrapped(terms.iter().map(|x| expr_to_repl(x))),
-        Expression::Assign { .. } => {
-            "".to_string() //TODO maybe the repl should say *something* here?
-        },
-        e => format!("Expression {:?} shouldn't be here", e),
-    }
-}
-
-impl Primitive {
-    fn to_repl(&self) -> String {
-        match self {
-            Primitive::Object { type_id, items, .. } => {
-                format!("{}{}", type_id.local_name(), paren_wrapped(items.iter().map(|item| item.to_repl())))
-            },
-            prim => expr_to_repl(&prim.to_expr()),
-        }
-    }
-}
 
 impl MemoryValue {
     fn to_repl(&self) -> String {
@@ -159,6 +134,23 @@ enum Primitive {
 }
 
 impl Primitive {
+    fn to_repl(&self) -> String {
+        match self {
+            Primitive::Object { type_id, items, .. } => {
+                format!("{}{}", type_id.local_name(), paren_wrapped(items.iter().map(|item| item.to_repl())))
+            },
+            Primitive::Literal(lit) => match lit {
+                Literal::Nat(n) => format!("{}", n),
+                Literal::Int(i) => format!("{}", i),
+                Literal::Float(f) => format!("{}", f),
+                Literal::Bool(b) => format!("{}", b),
+                Literal::StringLit(s) => format!("\"{}\"", s),
+            }
+            Primitive::Tuple(terms) => paren_wrapped(terms.iter().map(|x| x.to_repl())),
+            Primitive::Callable(..) => "<some-callable>".to_string(),
+        }
+    }
+
     fn unit() -> Self {
         Primitive::Tuple(vec![])
     }
@@ -170,24 +162,6 @@ impl From<Literal> for Primitive {
     }
 }
 
-impl Primitive {
-    fn to_expr(&self) -> Expression {
-        match self {
-            Primitive::Tuple(items) => Expression::Tuple(items.iter().map(|item| item.to_expr()).collect()),
-            Primitive::Literal(lit) => Expression::Literal(lit.clone()),
-            Primitive::Callable(function) => Expression::Callable(function.clone()),
-            Primitive::Object { type_id, tag, items } if items.len() == 0 => {
-                Expression::Literal(Literal::Nat(420))
-            },
-            Primitive::Object { type_id, tag, items } => Expression::Call {
-                f: Box::new(Expression::Callable(Callable::DataConstructor { type_id: type_id.clone(), arity: items.len() as u32, tag: *tag as u32 })),
-                args: items.iter().map(|arg| arg.to_expr()).collect(),
-            },
-        }
-    }
-}
-
-
 impl<'a> State<'a> {
     pub fn new() -> Self {
         Self {
@@ -334,10 +308,10 @@ impl<'a> State<'a> {
   fn apply_builtin(&mut self, builtin: Builtin, args: Vec<Expression>) -> EvalResult<Primitive> {
       use Builtin::*;
       use Literal::*;
-      use Expression::Literal as Lit;
+      use Primitive::Literal as Lit;
 
-      let evaled_args: EvalResult<Vec<Expression>> =
-          args.into_iter().map(|arg| self.expression(arg).map(|prim| prim.to_expr())).collect();
+      let evaled_args: EvalResult<Vec<Primitive>> =
+          args.into_iter().map(|arg| self.expression(arg)).collect();
       let evaled_args = evaled_args?;
 
       Ok(match (builtin, evaled_args.as_slice()) {
@@ -346,11 +320,11 @@ impl<'a> State<'a> {
           }
           /* builtin functions */
           (IOPrint, &[ref anything]) => {
-              print!("{}", expr_to_repl(anything));
+              print!("{}", anything.to_repl());
               Primitive::Tuple(vec![])
           },
           (IOPrintLn, &[ref anything]) => {
-              println!("{}", expr_to_repl(anything));
+              print!("{}", anything.to_repl());
               Primitive::Tuple(vec![])
           },
           (IOGetLine, &[]) => {