X-Git-Url: https://ruin.nu/git/?a=blobdiff_plain;f=Typecheck.hs;h=6f65d6e2f538d18d554787225c4aa138918a586f;hb=4f21d932178a490040cf5e054f3ba9d006579368;hp=52f9816b07fdc277cdb385a70ed5c3b3588b849b;hpb=9d0e3c89b286456549c68a816d0729f193498f6a;p=proglang.git

diff --git a/Typecheck.hs b/Typecheck.hs
index 52f9816..6f65d6e 100644
--- a/Typecheck.hs
+++ b/Typecheck.hs
@@ -1,11 +1,12 @@
 module Typecheck (typeCheckExp, typeCheckStm, typeCheckVar) where 
 
+
 import Abssyntax
 import Control.Monad.State
 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
@@ -23,16 +24,16 @@ typeCheckExp (BiOpExp e o e') = do
 					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
@@ -46,8 +47,12 @@ typeCheckExp (ENot e) = do
 
 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
@@ -55,7 +60,9 @@ typeCheckStm (SExp e) = do
 	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
@@ -69,9 +76,9 @@ typeCheckStm (SWhile e s) = do
 typeCheckStm (SDecl t i e) = do
 	t2 <- typeCheckExp e
 	if t == t2 || t2 == NoType then do
-		m <- get
-		case insertLookupWithKey (\k a1 a2 -> a1) i t m of 
-			(Nothing,m') -> put m'
+		(m:ms) <- get
+		case insertLookupWithKey (\k a1 a2 -> a1) i t m of
+			(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