X-Git-Url: https://ruin.nu/git/?p=proglang.git;a=blobdiff_plain;f=Interpret.hs;h=fd04dcd722d9e33d8b65a70c292c96bd161e48e4;hp=9e4dcff34541b1f180b73b3c12dc15cbcfb3e642;hb=d553df8dfdffca78342d6fae142ceded9cd64415;hpb=4f21d932178a490040cf5e054f3ba9d006579368

diff --git a/Interpret.hs b/Interpret.hs
index 9e4dcff..fd04dcd 100644
--- a/Interpret.hs
+++ b/Interpret.hs
@@ -23,7 +23,6 @@ eval (EBool b) = return (VBool b)
 eval (EInt n) = return (VInt n)
 eval (EVar i) = getVariableValue i
 eval (EAss i e) = setVariableValue i e 
-eval EDefault = error "EDefault called from an illegal place"
 eval (BiOpExp e o e') = do
 	v <- eval e
 	v'<- eval e'
@@ -78,11 +77,6 @@ findVariable i (m:ms) = if member i m then lookup i m else findVariable i ms
 
 --setVariableValue :: (MonadState Variables m) => Ident -> Exp -> m Value 
 --setVariableValue :: (MonadState Variables m) => Ident -> Exp -> m Value 
-addVariable :: Ident -> Exp -> StateT Variables IO ()
-addVariable i e = do
-	e' <- eval e
-	(m:ms) <- get
-	put $ (insert i e' m):ms
 
 setVariableValue :: Ident -> Exp -> StateT Variables IO Value
 setVariableValue i e = do
@@ -95,6 +89,11 @@ updateVariable :: Ident -> Value -> Variables -> Variables
 updateVariable _ _ [] = []
 updateVariable i v (m:ms) = if member i m then insert i v m:ms else m:updateVariable i v ms
 
+pushAndPop :: (MonadState Variables m) => m a -> m ()
+pushAndPop s = do
+	modify (empty:)
+	s
+	modify tail
 
 -- execute :: (MonadState Variables m) => Stm -> m ()
 execute :: Stm -> StateT Variables IO ()
@@ -102,20 +101,19 @@ execute (SNoop) = return ()
 execute (SExp e) = eval e >> return ()
 execute (SIf b s s') = do
 	(VBool b') <- eval b
-	if b' then execute s else execute s'
+	pushAndPop $ if b' then execute s else execute s'
 execute (SPrint e) = do
 	e' <- eval e
 	lift $ print e'
-execute (SBlock ss) = do
-	modify (empty:)
-	mapM execute ss
-	modify tail
+execute (SBlock ss) = pushAndPop $ mapM execute ss
 execute (SWhile e s) = do
 	(VBool b) <- eval e
-	if b then execute s >> execute (SWhile e s) else return ()
-execute (SDecl t i EDefault) = do
-	case t of
-		TInt -> addVariable i (EInt 0)
-		TBool -> addVariable i (EBool False)
-	return ()
-execute (SDecl t i e) = addVariable i e >> return ()
+	if b then pushAndPop (execute s) >> execute (SWhile e s) else return ()
+execute (SDeclD t i) = execute (SDecl t i $ case t of
+	TInt -> EInt 0
+	TBool -> EBool False
+	)
+execute (SDecl t i e) =do
+	e' <- eval e
+	(m:ms) <- get
+	put $ (insert i e' m):ms