type instance for FunDecl

diff --git a/sem.icl b/sem.icl
index 272ef5a..24943fe 100644 (file)
--- a/sem.icl
+++ b/sem.icl
@@ -281,14 +281,14 @@ instance infer Stmt where
         infer el >>= \(s4, elt)->
         applySubst s4 >>|
         lift (unify tht elt) >>= \s5-> 
-        pure (compose s5 $ compose s4 $ compose s3 $ compose s1 s2, subst s5 tht)
+        pure (compose s5 $ compose s4 $ compose s3 $ compose s2 s1, subst s5 tht)
 
     WhileStmt e wh = 
         infer e >>= \(s1, et)->
         lift (unify et BoolType) >>= \s2 ->
         applySubst (compose s2 s1) >>|
         infer wh >>= \(s3, wht)->
-        pure (compose s3 $ compose s1 s2, subst s3 wht)
+        pure (compose s3 $ compose s2 s1, subst s3 wht)
 
     AssStmt (VarDef k fs) e =
         infer e >>= \(s1, et)->
@@ -301,15 +301,53 @@ instance infer Stmt where
     ReturnStmt Nothing = pure (zero, VoidType)
     ReturnStmt (Just e) = infer e
 
-
+//The type of a list of statements is either an encountered
+//return, or VoidType
 instance infer [a] | infer a where
-    infer _ = undef
+    infer []        = pure (zero, VoidType)
+    infer [stmt:ss] = 
+        infer stmt >>= \(s1, t1) ->
+        infer ss >>= \(s2, t2) ->
+        case t1 of
+            VoidType = pure (compose s2 s1, t2)
+            _ = case t2 of
+                VoidType = pure (compose s2 s1, t1)
+                _ = lift (unify t1 t2) >>= \s3 -> 
+                    pure (compose s3 $ compose s2 s1, t1)
+
+//the type class inferes the type of an AST element (VarDecl or FunDecl)
+//and adds it to the AST element
+class type a :: a -> Typing a
+
+instance type VarDecl where
+    type (VarDecl p expected k e) = 
+        infer e >>= \(s, given) ->
+        applySubst s >>| 
+        case expected of
+            Nothing = pure zero
+            Just expected_ = lift (unify expected_ given)
+        >>|
+        generalize given >>= \t ->
+        changeGamma (extend k t) >>| 
+        pure (VarDecl p (Just given) k e)
+
+instance type FunDecl where
+    type (FunDecl p f args expected vds stmts) = 
+        type vds >>= \tVds->
+        infer stmts >>= \(s, given)->
+        applySubst s >>|
+        (case expected of
+            Nothing = pure zero
+            Just expected_ = lift (unify expected_ given))
+        >>|
+        generalize given >>= \t->
+        changeGamma (extend f t) >>| 
+        pure (FunDecl p f args (Just given) tVds stmts)
+
+instance type [a] | type a where
+    type dcls = mapM type dcls
+
 
-Mapmap :: (a->b) ('Map'.Map k a) -> ('Map'.Map k b)
-Mapmap _ 'Map'.Tip = 'Map'.Tip
-Mapmap f ('Map'.Bin sz k v ml mr) = 'Map'.Bin sz k (f v) 
-                                        (Mapmap f ml) 
-                                        (Mapmap f mr)
 
 instance toString Scheme where
     toString (Forall x t) = 
@@ -327,6 +365,12 @@ instance toString SemError where
 instance MonadTrans (StateT (Gamma, [TVar])) where
     liftT m = StateT \s-> m >>= \a-> return (a, s)
 
+Mapmap :: (a->b) ('Map'.Map k a) -> ('Map'.Map k b)
+Mapmap _ 'Map'.Tip = 'Map'.Tip
+Mapmap f ('Map'.Bin sz k v ml mr) = 'Map'.Bin sz k (f v) 
+                                        (Mapmap f ml) 
+                                        (Mapmap f mr)
+
 //// ------------------------
 //// First step: Inference
 //// ------------------------//