+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
+
+assert :: Monad m => Bool -> String -> m ()
+assert True _ = return ()
+assert False s = fail s
+
+typeCheckExp :: (MonadState Types m) => Exp -> m Type
+typeCheckExp (BiOpExp e o e') = do
+ t1 <- typeCheckExp e
+ t2 <- typeCheckExp e'
+ assert (t1 == t2) "The parameters for the binary operator aren't equal"
+ if inList o [Eq,NEq] then return TBool
+ else do
+ assert (t1 == TInt) "The parameters need to be of type int"
+ if inList o [Plus,Minus,Times,Div]
+ then return TInt
+ else return TBool
+typeCheckExp (EVar i) = typeCheckVar i
+typeCheckExp (EAss i e) = do
+ t <- typeCheckVar i
+ t2 <- typeCheckExp e
+ assert (t == t2) $ "Illegal to assign an expression of type "++show t2++" to variable "++show i++" of type "++show t
+ return t
+typeCheckExp (EInt i) = return TInt
+typeCheckExp (EBool b) = return TBool
+typeCheckExp EReadI = return TInt
+typeCheckExp EReadB = return TBool
+typeCheckExp (EPost i op) = do
+ TInt <- typeCheckVar i
+ return TInt
+typeCheckExp (ENeg e) = do
+ TInt <- typeCheckExp e