added not

[proglang.git] / Typecheck.hs

diff --git a/Typecheck.hs b/Typecheck.hs
index 6e845ba2cb56b9625570676c65e6354da53eb4ba..52f9816b07fdc277cdb385a70ed5c3b3588b849b 100644 (file)
--- a/Typecheck.hs
+++ b/Typecheck.hs
@@ -5,7 +5,6 @@ import Control.Monad.State
 import Data.Map as Map
 import Prelude hiding (lookup)
 
-
 type Types = Map Ident Type
 
 inList :: Eq a => a -> [a] -> Bool
@@ -16,13 +15,12 @@ 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
@@ -42,7 +40,9 @@ typeCheckExp (EPost i op) = do
 typeCheckExp (ENeg e) = do
        TInt <- typeCheckExp e
        return TInt
-
+typeCheckExp (ENot e) = do
+       TBool <- typeCheckExp e
+       return TBool
 
 typeCheckVar :: (MonadState Types m) => Ident -> m Type 
 typeCheckVar i = do
@@ -70,10 +70,11 @@ 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
        typeCheckExp e
        return NoType
-