Support function arguments.

1 files changed, 26 insertions, 10 deletions

diff --git a/elab.sml b/elab.sml
index 6a80715..032d1d7 100644
--- a/elab.sml
+++ b/elab.sml
@@ -1,31 +1,47 @@
 structure Elab =
 struct
+  structure StringMap = Map(type k = string val cmp = String.compare);
+
   fun primop (s : string) : Syntax.primop =
     case s of
       "exit" => Syntax.PExit
     | _ => raise Fail ("invalid op: " ^ s)
 
-  fun elaborate (p : Syntax.expr) : Syntax.lexp =
+  fun elab (env : int StringMap.map) (p : Syntax.expr) : Syntax.lexp =
     case p of
-      Syntax.EIdent [i] => raise Fail "only primitive operations for now, no variables"
+      Syntax.EIdent [i] => (case StringMap.lookup i env of
+        NONE => raise Fail ("unbound identifier " ^ i)
+      | SOME x => Syntax.LVar x)
     | Syntax.EIdent _ => raise Fail "long identifiers are not supported"
     | Syntax.EBuiltin builtin => Syntax.LPrim (primop builtin)
     | Syntax.EInt i => Syntax.LInt i
     | Syntax.EStr s => Syntax.LString s
-    | Syntax.ETuple exprs => Syntax.LRecord (map elaborate exprs)
+    | Syntax.ETuple exprs => Syntax.LRecord (map (elab env) exprs)
     | Syntax.EList exprs =>
         foldr
           (fn (x, acc) =>
-            Syntax.LRecord [elaborate x, acc])
+            Syntax.LRecord [elab env x, acc])
           (Syntax.LInt 0)
           exprs
-    | Syntax.EApp (f, x) => Syntax.LApp (elaborate f, elaborate x)
-    | Syntax.ETyped (e, _) => elaborate e
+    | Syntax.EApp (f, x) => Syntax.LApp (elab env f, elab env x)
+    | Syntax.ETyped (e, _) => elab env e
     | Syntax.EAndAlso (_, _) => raise Fail "unimplemented"
     | Syntax.EOrElse (_, _) => raise Fail "unimplemented"
     | Syntax.ELet (decls, body) =>
-        Syntax.LRecord
-          (map elaborate
-            (map (fn (Syntax.DVal e) => e) decls @ [body]))
-    | Syntax.ELambda e => Syntax.LFn (Gensym.new (), elaborate e)
+        foldr
+          (fn (Syntax.DVal v, acc) =>
+            Syntax.LApp (Syntax.LFn (Gensym.new (), acc), elab env v))
+          (elab env body)
+          decls
+    | Syntax.ELambda (var, body) =>
+        let
+          val v = Gensym.new ()
+          val env' =
+            case var of
+              Syntax.PWild => env
+            | Syntax.PVar name => StringMap.insert name v env
+        in Syntax.LFn (v, elab env' body)
+        end
+
+  fun elaborate (p : Syntax.expr) : Syntax.lexp = elab StringMap.empty p
 end