streamlined the binary operators

[proglang.git] / Typecheck.hs

diff --git a/Typecheck.hs b/Typecheck.hs
index ec2270e01c3860215b28dcb851807b8f8f14ea99..6e845ba2cb56b9625570676c65e6354da53eb4ba 100644 (file)
--- a/Typecheck.hs
+++ b/Typecheck.hs
@@ -1,4 +1,4 @@
-module Typecheck where 
+module Typecheck (typeCheckExp, typeCheckStm, typeCheckVar) where 
 
 import Abssyntax
 import Control.Monad.State
@@ -8,15 +8,21 @@ import Prelude hiding (lookup)
 
 type Types = Map Ident Type
 
+inList :: Eq a => a -> [a] -> Bool
+inList _ [] = False
+inList a (x:xs) = if a == x then True else inList a xs
+
 typeCheckExp :: (MonadState Types m) => Exp -> m Type
-typeCheckExp (BExp e o e') = do
-       TInt <- typeCheckExp e
-       TInt <- typeCheckExp e'
-       return TBool
-typeCheckExp (OpExp e o e') = do
-       TInt <- typeCheckExp e
-       TInt <- typeCheckExp e'
-       return TInt
+typeCheckExp (BiOpExp e o e') = do
+       t1 <- typeCheckExp e
+       t2 <- typeCheckExp e'
+       if not(t1 == t2) then fail "" 
+               else case inList o [Eq,NEq] of
+                       True -> return TBool
+                       False -> if not(t1 == TInt) then fail "" 
+                               else case inList o [Plus,Minus,Times,Div] of
+                                       True -> return TInt
+                                       False -> return TBool
 typeCheckExp (EVar i) = typeCheckVar i
 typeCheckExp (EAss i e) = do
        a <- typeCheckVar i
@@ -33,6 +39,9 @@ typeCheckExp EDefault = return NoType
 typeCheckExp (EPost i op) = do
        TInt <- typeCheckVar i
        return TInt
+typeCheckExp (ENeg e) = do
+       TInt <- typeCheckExp e
+       return TInt
 
 
 typeCheckVar :: (MonadState Types m) => Ident -> m Type 
@@ -59,11 +68,11 @@ typeCheckStm (SWhile e s) = do
        return NoType
 typeCheckStm (SDecl t i e) = do
        t2 <- typeCheckExp e
-       if t == t2 then do
+       if t == t2 || t2 == NoType then do
                m <- get
                put (insert i t m)
                return NoType
-               else fail "Så får du inte göra!!!"
+               else fail $ "Illegal to assign an expression of type "++show t2++" to variable "++show i++" of type "++show t
 typeCheckStm (SPrint e) = do
        typeCheckExp e
        return NoType