import Data.Map as Map
import Prelude hiding (lookup)
-type Types = Map Ident Type
+type Types = [Map Ident Type]
inList :: Eq a => a -> [a] -> Bool
inList _ [] = False
else return TBool
typeCheckExp (EVar i) = typeCheckVar i
typeCheckExp (EAss i e) = do
- a <- typeCheckVar i
- b <- typeCheckExp e
- if a == b then return a else fail "FEL!"
+ t <- typeCheckVar i
+ t2 <- typeCheckExp e
+ if t == t2 then return t else fail $ "Illegal to assign an expression of type "++show t2++" to variable "++show i++" of type "++show t
typeCheckExp (EInt i) = return TInt
typeCheckExp (EBool b) = return TBool
typeCheckExp EReadI = return TInt
typeCheckExp EReadB = return TBool
typeCheckExp (ExpT t e) = do
t2 <- typeCheckExp e
- if t == t2 then return t else fail "FEL!"
+ if t == t2 then return t else fail "Something went wrong ExpT is created with the wrong type"
typeCheckExp EDefault = return NoType
typeCheckExp (EPost i op) = do
TInt <- typeCheckVar i
typeCheckVar :: (MonadState Types m) => Ident -> m Type
typeCheckVar i = do
- e <- get
- lookup i e
+ ms <- get
+ findVariable i ms
+
+findVariable :: (MonadState Types m) => Ident -> Types -> m Type
+findVariable i [] = fail $ "Variable "++show i++" not found in any scope."
+findVariable i (m:ms) = if member i m then lookup i m else findVariable i ms
typeCheckStm :: (MonadState Types m) => Stm -> m Type
typeCheckStm SNoop = return NoType
typeCheckExp e
return NoType
typeCheckStm (SBlock ss) = do
+ modify (empty:)
mapM typeCheckStm ss
+ modify tail
return NoType
typeCheckStm (SIf e s s') = do
TBool <- typeCheckExp e
typeCheckStm (SDecl t i e) = do
t2 <- typeCheckExp e
if t == t2 || t2 == NoType then do
- m <- get
+ (m:ms) <- get
case insertLookupWithKey (\k a1 a2 -> a1) i t m of
- (Nothing,m') -> put m'
+ (Nothing,m') -> put (m':ms)
_ -> 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