Support Let

1 files changed, 8 insertions, 0 deletions

diff --git a/typecheck/CC/Typecheck.hs b/typecheck/CC/Typecheck.hs
index 8678771..8803a62 100644
--- a/typecheck/CC/Typecheck.hs
+++ b/typecheck/CC/Typecheck.hs
@@ -87,6 +87,8 @@ instance Substitute Env where
 instance Substitute T.Expr where
     theta >>! T.Lam ty (T.Occ name ty2) body =
         T.Lam (theta >>! ty) (T.Occ name (theta >>! ty2)) (theta >>! body)
+    theta >>! T.Let (T.Occ name ty) rhs body =
+        T.Let (T.Occ name (theta >>! ty)) (theta >>! rhs) (theta >>! body)
     theta >>! T.Call ty e1 e2 =
         T.Call (theta >>! ty) (theta >>! e1) (theta >>! e2)
     _     >>! expr@(T.Int _) = expr
@@ -152,6 +154,12 @@ infer env expr = case expr of
         let argType = theta >>! argVar
         return (theta, T.Lam (T.TFun argType (T.exprType body'))
                              (T.Occ arg argType) body')
+    S.Let _ (name, _) rhs body -> do
+        (theta1, rhs') <- infer env rhs
+        let varType = T.exprType rhs'
+        let augEnv = envAdd name (T.TypeScheme [] varType) env
+        (theta2, body') <- infer augEnv body
+        return (theta2 <> theta1, T.Let (T.Occ name varType) rhs' body')
     S.Call sr func arg -> do
         (theta1, func') <- infer env func
         (theta2, arg') <- infer (theta1 >>! env) arg