X-Git-Url: https://ruin.nu/git/?p=proglang.git;a=blobdiff_plain;f=Interpret.hs;h=62cc7fd9d5f839978692359779b16ecc9c465e92;hp=5e18d88b07046182de7c51ed0866d1e18c82691d;hb=HEAD;hpb=41bc48c79195f018687fef2ba64e4c87bb7a206b

diff --git a/Interpret.hs b/Interpret.hs
index 5e18d88..62cc7fd 100644
--- a/Interpret.hs
+++ b/Interpret.hs
@@ -28,7 +28,6 @@ interpret fun st = do
 	runStateT (runErrorT  (do mapM addFunction fun; mapM_ execute st)) emptyState
 	return ()
 
---eval :: (MonadState State m, MonadError String m, MonadIO m) => Exp -> m Value
 eval :: (MonadState State m, MonadIO m) => Exp -> EvalM m Value
 eval (EBool b) = return (VBool b)
 eval (EInt n) = return (VInt n)
@@ -40,7 +39,7 @@ eval (BiOpExp e o e') = do
 	v <- eval e
 	v'<- eval e'
 	if elem o [Eq,NEq] then return $ opE o v v'
-		else let (VInt n1) = v in let (VInt n2) = v' in return $ op o n1 n2
+		else let (VInt n1) = v in let (VInt n2) = v' in return $! op o n1 n2
 eval (EPost i o) = do
 	(VInt n) <- getVariableValue i
 	setVariableValue i $ op o n 1
@@ -65,15 +64,15 @@ eval (EFunc i as) = do
 		in modify (\s -> s{variables=[m]})
 	(mapM_ execute ss >> (fail $ "Function "++show i++" didn't return anything."))
 		`catchError` (\_ ->return ()) --Only errors thrown in ErrorT can be caught here, runtime errors pass through, so no need to check the error
-	state' <- get
+	v <- liftM ret get
 	put state
-	return $ ret state'
+	return v
 
 --Stricter evaluation of the input
 getNumber :: IO String
 getNumber = do
 	c <- getChar
-	if elem c ['-','0'..'9']
+	if elem c $ '-':['0'..'9']
 		then do
 			l <- getNumber2
 			return (c:l)
@@ -89,16 +88,17 @@ getNumber2 =  do
 		else return ""
 
 -- op :: Op -> (a -> a -> Value)
-opE Eq = \e e' -> VBool $ e == e'
-opE NEq = \e e' -> VBool $ not (e == e')
-op Plus = \e e' -> VInt $ e + e'
-op Minus = \e e' -> VInt $ e - e'
-op Times = \e e' -> VInt $ e * e'
-op Div = \e e' -> VInt $ e `div` e'
-op Lt = \e e' -> VBool $ e < e'
-op ELt = \e e' -> VBool $ e <= e'
-op Gt = \e e' -> VBool $ e > e'
-op EGt = \e e' -> VBool $ e >= e'
+opE Eq e e' = VBool $ e == e'
+opE NEq e e' = VBool $ not (e == e')
+op Plus e e' =VInt $ e + e'
+op Minus e e' = VInt $ e - e'
+op Times e e' = VInt $ e * e'
+op Div _ 0 = error "Division by zero"
+op Div e e' = VInt $ e `div` e'
+op Lt e e' = VBool $ e < e'
+op ELt e e' = VBool $ e <= e'
+op Gt e e' = VBool $ e > e'
+op EGt e e' = VBool $ e >= e'
 
 getVariableValue :: (MonadState State m) => Ident -> m Value 
 getVariableValue i = do
@@ -124,7 +124,6 @@ pushAndPop s = do
 	s
 	modify (\s -> s { variables = tail $ variables s})
 
--- execute :: (MonadState Variables m) => Stm -> m ()
 execute :: (MonadState State m, MonadIO m) => Stm -> EvalM m ()
 execute (SNoop) = return ()
 execute (SExp e) = eval e >> return ()
@@ -143,8 +142,8 @@ execute (SDeclD t i) = execute $ SDecl t i $ case t of
 	TBool -> EBool False
 execute (SDecl t i e) =do
 	v <- eval e
-	state <- get
-	let (m:ms) = variables state in modify (\s -> s{variables=insert i v m:ms })
+	(m:ms) <- liftM variables get
+	modify (\s -> s{variables=insert i v m:ms })
 execute (SReturn e) = do
 	v <- eval e
 	modify (\s -> s{ret=v})