X-Git-Url: https://ruin.nu/git/?p=proglang.git;a=blobdiff_plain;f=Interpret.hs;h=62cc7fd9d5f839978692359779b16ecc9c465e92;hp=948903ebd9416e6de394f62cc4c27772eacd96b0;hb=HEAD;hpb=e4867d1f76874882921ec9501d20834a4d96eb5a

diff --git a/Interpret.hs b/Interpret.hs
index 948903e..62cc7fd 100644
--- a/Interpret.hs
+++ b/Interpret.hs
@@ -21,27 +21,28 @@ type Function = ([Decl],[Stm])
 
 data State = State {variables::Variables,functions::(Map Ident Function),ret::Value}
 
-type EvalM = ErrorT String (StateT State IO)
+type EvalM m = ErrorT String m
 
 interpret :: [Func] -> [Stm] -> IO ()
 interpret fun st = do
-	runStateT (runErrorT  (do mapM Interpret.addFunction fun; mapM_ execute st)) emptyState
+	runStateT (runErrorT  (do mapM addFunction fun; mapM_ execute st)) emptyState
 	return ()
 
---eval :: (MonadState Variables m) => Exp -> m Value
-eval :: Exp -> EvalM Value
+eval :: (MonadState State m, MonadIO m) => Exp -> EvalM m Value
 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 (EAss i e) = do 
+	v <- eval e
+	setVariableValue i v
 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
-	let (VInt n') = op o n 1 in setVariableValue i $ EInt n'
+	setVariableValue i $ op o n 1
 	return $ VInt n
 eval (ENeg e) = do
 	(VInt n) <- eval e
@@ -50,10 +51,10 @@ eval (ENot e) = do
 	(VBool b) <- eval e
 	return $ VBool $ not b
 eval EReadI = do
-	s <- liftIO $ getWord
+	s <- liftIO $ getNumber
 	return $ VInt $ read s
 eval EReadB = do
-	s <- liftIO $ getWord
+	s <- liftIO $ getNumber
 	return $ VBool $ if (read s == 0) then False else True
 eval (EFunc i as) = do
 	vs <- mapM eval as
@@ -61,46 +62,56 @@ eval (EFunc i as) = do
 	(ds,ss) <- lookup i $ functions state
 	let m = foldr (\((Decl t i),v) m -> insert i v m) empty $ zip ds vs
 		in modify (\s -> s{variables=[m]})
-	mapM_ execute ss `catchError` (\_ -> return ())
-	s <- get
+	(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
+	v <- liftM ret get
 	put state
-	return $ ret s
+	return v
+
+--Stricter evaluation of the input
+getNumber :: IO String
+getNumber = do
+	c <- getChar
+	if elem c $ '-':['0'..'9']
+		then do
+			l <- getNumber2
+			return (c:l)
+		else fail "Non integer input."
 
-getWord :: IO String
-getWord =  do
+getNumber2 :: IO String
+getNumber2 =  do
 	c <- getChar
-	if elem c [' ', '\n', '\t', '\r']
-		then return ""
-		else do
-			l <- getWord
+	if elem c ['0'..'9']
+		then do
+			l <- getNumber2
 			return (c:l)
+		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
 	s <- get 
 	findVariable i $ variables s
 
-findVariable :: (MonadState State m) => Ident -> Variables -> m Value
+findVariable :: (Monad m) => Ident -> Variables -> m Value
 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
 
-setVariableValue :: Ident -> Exp -> EvalM Value
-setVariableValue i e = do
-	v <- eval e
-	state <- get
-	modify (\s -> s{variables= updateVariable i v $ variables state} )
+setVariableValue :: (MonadState State m) => Ident -> Value -> EvalM m Value
+setVariableValue i v = do
+	modify (\s -> s{variables= updateVariable i v $ variables s} )
 	return v
 
 updateVariable :: Ident -> Value -> Variables -> Variables 
@@ -113,8 +124,7 @@ pushAndPop s = do
 	s
 	modify (\s -> s { variables = tail $ variables s})
 
--- execute :: (MonadState Variables m) => Stm -> m ()
-execute :: Stm -> EvalM ()
+execute :: (MonadState State m, MonadIO m) => Stm -> EvalM m ()
 execute (SNoop) = return ()
 execute (SExp e) = eval e >> return ()
 execute (SIf b s s') = do
@@ -132,8 +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})