X-Git-Url: https://ruin.nu/git/?a=blobdiff_plain;f=Typecheck.hs;h=2414203d7d81441d89080f3c3dc8d5486f140600;hb=d2416679eff983d31ea9b2de4bdd0124c50bd20d;hp=6e845ba2cb56b9625570676c65e6354da53eb4ba;hpb=6103c0359b95557566aa9154efa5bcd4d9c996f6;p=proglang.git

diff --git a/Typecheck.hs b/Typecheck.hs
index 6e845ba..2414203 100644
--- a/Typecheck.hs
+++ b/Typecheck.hs
@@ -16,13 +16,12 @@ typeCheckExp :: (MonadState Types m) => Exp -> m Type
 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
+	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
@@ -70,7 +69,9 @@ typeCheckStm (SDecl t i e) = do
 	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