Implement recursive functions.

1 files changed, 12 insertions, 0 deletions

diff --git a/elab.sml b/elab.sml
index f6f2e38..af6bec2 100644
--- a/elab.sml
+++ b/elab.sml
@@ -34,6 +34,18 @@ struct
     | Syntax.ELet ([], body) => elab env body
     | Syntax.ELet (Syntax.DVal (pat, v) :: decls, body) =>
         elab env (Syntax.ECase (v, [(pat, Syntax.ELet (decls, body))]))
+    | Syntax.ELet (Syntax.DValRec (Syntax.PVar name, f as Syntax.ELambda _) :: decls, body) =>
+        let
+          val n = Gensym.new ()
+          val env' = StringMap.insert name n env
+          val (arg, fnBody) =
+            case elab env' f of
+              Syntax.LFn x => x
+            | _ => raise Fail "Syntax.ELambda should expand to Syntax.LFn"
+        in
+          Syntax.LFix ([(n, arg, fnBody)], elab env' (Syntax.ELet (decls, body)))
+        end
+    | Syntax.ELet (Syntax.DValRec _ :: _, _) => raise Fail "invalid val rec"
     | Syntax.ELambda (pat, body) =>
         let
           val v = Gensym.new ()