Return codes in Main.hs

1 files changed, 8 insertions, 1 deletions

diff --git a/src/Main.hs b/src/Main.hs
index 07733dd..72c577a 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -3,6 +3,7 @@ module Main where
 
 import Prelude hiding(lex)
 import System.Environment
+import System.Exit
 
 import Text.Parsec.Error (ParseError)
 
@@ -16,7 +17,9 @@ main = do
   args <- getArgs
   contents <- getContents
   case lex contents of
-    Nothing  -> putStrLn "Failed to lex"
+    Nothing  -> do
+      putStrLn "Failed to lex"
+      exit 1
     Just tks -> if "--parse" `elem` args
       then doParse tks
       else return ()
@@ -26,4 +29,8 @@ main = do
       Left e -> do
         putStrLn $ "Failed to parse (" ++ show e ++ "). Tokens were:"
         putStrLn $ show tks
+        exit 1
       Right pgm -> putStrLn $ prettyPrint pgm
+
+    exit :: Int -> IO ()
+    exit = exitWith . ExitFailure