Added default functions, isEmpty does not typecheck...

[cc1516.git] / sem.icl

diff --git a/sem.icl b/sem.icl
index 34675d2..0da9c77 100644 (file)
--- a/sem.icl
+++ b/sem.icl
@@ -26,7 +26,6 @@ from Text import class Text(concat), instance Text String
 
 import AST
 
-
 :: Scheme = Forall [TVar] Type
 :: Gamma :== 'Map'.Map String Scheme //map from Variables! to types
 :: Typing a :== StateT (Gamma, [TVar]) (Either SemError) a
@@ -49,13 +48,19 @@ instance zero Gamma where
 variableStream :: [TVar]
 variableStream = map toString [1..]
 
+defaultGamma :: Gamma //includes all default functions
+defaultGamma = extend "print" (Forall ["a"] ((IdType "a") ->> VoidType))
+                $ extend "isEmpty" (Forall ["a"] (ListType (IdType "a") ->> BoolType))
+                $ extend "read" (Forall [] (IntType ->> (ListType CharType)))
+                zero
+
 sem :: AST -> Either [SemError] AST
 sem (AST fd) = case foldM (const $ hasNoDups fd) () fd 
                        >>| foldM (const isNiceMain) () fd
                        >>| hasMain fd
-                    >>| evalStateT (type fd) (zero, variableStream) of
+                    >>| evalStateT (type fd) (defaultGamma, variableStream) of
        Left e = Left [e]
-    Right fds = Right (AST fds)
+    Right (_,fds) = Right (AST fds)
 where
                hasNoDups :: [FunDecl] FunDecl -> Either SemError ()
                hasNoDups fds (FunDecl p n _ _ _ _)
@@ -173,6 +178,7 @@ generalize :: Type -> Typing Scheme
 generalize t = gamma >>= \g-> pure $ Forall (difference (ftv t) (ftv g)) t
 
 lookup :: String -> Typing Type 
+lookup "isEmpty" = ListType <$> fresh
 lookup k = gamma >>= \g-> case 'Map'.member k g of
     False = liftT (Left $ UndeclaredVariableError zero k)
     True = instantiate $ 'Map'.find k g
@@ -270,12 +276,15 @@ instance infer Stmt where
         pure (compose s3 $ compose s2 s1, subst s3 wht)
 
     AssStmt (VarDef k fs) e =
-        infer e >>= \(s1, et)->
-        applySubst s1 >>|
-        changeGamma (extend k (Forall [] et)) >>| //todo: fieldselectors
-        pure (s1, VoidType)
+        lookup k >>= \expected ->
+        infer e >>= \(s1, given)->
+        lift (unify expected given) >>= \s2->
+        let s = compose s2 s1 in
+        applySubst s >>|
+        changeGamma (extend k (Forall [] given)) >>| //todo: fieldselectors
+        pure (s, VoidType)
 
-    FunStmt f es = undef //what is this? 
+    FunStmt f es = pure (zero, VoidType) 
 
     ReturnStmt Nothing = pure (zero, VoidType)
     ReturnStmt (Just e) = infer e
@@ -298,7 +307,7 @@ instance infer [a] | infer a where
 
 //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
+class type a :: a -> Typing (Substitution, a)
 
 instance type VarDecl where
     type (VarDecl p expected k e) = 
@@ -312,31 +321,38 @@ instance type VarDecl where
         let vtype = subst (compose s2 s1) given in
         generalize vtype >>= \t ->
         changeGamma (extend k t) >>| 
-        pure (VarDecl p (Just vtype) k e)
+        pure (compose s2 s1, VarDecl p (Just vtype) k e)
 
 instance type FunDecl where
     type (FunDecl p f args expected vds stmts) = 
+        gamma >>= \outerScope-> //functions are infered in their own scopde
         introduce f >>|
         mapM introduce args >>= \argTs->
-        type vds >>= \tVds->
-        infer stmts >>= \(s1, result)->
-        let given = foldr (->>) result argTs in 
+        type vds >>= \(s1, tVds)->
+        applySubst s1 >>|
+        infer stmts >>= \(s2, result)->
         applySubst s1 >>|
+        let argTs_ = map (subst $ compose s2 s1) argTs in 
+        //abort (concat $ intersperse "\n" $ map toString argTs_) >>|
+        let given = foldr (->>) result argTs_ in 
         (case expected of
             Nothing = pure zero
             Just expected_ = lift (unify expected_ given))
-        >>= \s2 ->
-        let ftype = subst (compose s2 s1) given in
+        >>= \s3 ->
+        let ftype = subst (compose s3 $ compose s2 s1) given in
         generalize ftype >>= \t->
+        putGamma outerScope >>|
         changeGamma (extend f t) >>| 
-        pure (FunDecl p f args (Just ftype) tVds stmts)
-
-instance toString (Maybe a) | toString a where
-    toString Nothing = "Nothing"
-    toString (Just e) = concat ["Just ", toString e]
+        pure (compose s3 $ compose s2 s1, FunDecl p f args (Just ftype) tVds stmts)
 
 instance type [a] | type a where
-    type dcls = mapM type dcls
+    type []     = pure (zero, [])
+    type [v:vs] = 
+        type v >>= \(s1, v_)->
+        applySubst s1 >>|
+        type vs >>= \(s2, vs_)->
+        applySubst (compose s2 s1) >>|
+        pure (compose s2 s1, [v_:vs_])
 
 introduce :: String -> Typing Type
 introduce k = 
@@ -379,6 +395,10 @@ instance toString SemError where
     toString (Error e) = concat ["Unknown error during semantical",
         "analysis: ", e]
 
+instance toString (Maybe a) | toString a where
+    toString Nothing = "Nothing"
+    toString (Just e) = concat ["Just ", toString e]
+
 instance MonadTrans (StateT (Gamma, [TVar])) where
     liftT m = StateT \s-> m >>= \a-> return (a, s)