-module Typecheck where
+module Typecheck (typeCheckExp, typeCheckStm, typeCheckVar) where
import Abssyntax
import Control.Monad.State
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 "The parameters for the binary operator aren't equal"
+ else if inList o [Eq,NEq] then return TBool
+ else if not(t1 == TInt) then fail "The parameters need to be of type int"
+ else if inList o [Plus,Minus,Times,Div]
+ then return TInt
+ else return TBool
typeCheckExp (EVar i) = typeCheckVar i
typeCheckExp (EAss i e) = do
a <- typeCheckVar i
t2 <- typeCheckExp e
if t == t2 || t2 == NoType then do
m <- get
- put (insert i t m)
+ case insertLookupWithKey (\k a1 a2 -> a1) i t m of
+ (Nothing,m') -> put m'
+ _ -> fail $ "Duplicate variable declaration: "++show i
return NoType
else fail $ "Illegal to assign an expression of type "++show t2++" to variable "++show i++" of type "++show t
typeCheckStm (SPrint e) = do