Fix double-warning issue

paf31 · paf31 · commit 6a378be5ac33 · 2015-10-26T14:13:03.000-07:00
diff --git a/src/Control/Monad/Logger.hs b/src/Control/Monad/Logger.hs
@@ -57,15 +57,13 @@ instance (Monoid w) => MonadIO (Logger w) where
   liftIO = Logger . const
 
 instance (Monoid w) => MonadWriter w (Logger w) where
-  tell w = Logger $ \r -> modifyIORef' r (mappend w)
+  tell w = Logger $ \r -> atomicModifyIORef' r $ \w' -> (mappend w' w, ())
   listen l = Logger $ \r -> do
     (a, w) <- liftIO (runLogger' l)
-    modifyIORef' r (mappend w)
-    return (a, w)
+    atomicModifyIORef' r $ \w' -> (mappend w' w, (a, w))
   pass l = Logger $ \r -> do
     ((a, f), w) <- liftIO (runLogger' l)
-    modifyIORef' r (mappend (f w))
-    return a
+    atomicModifyIORef' r $ \w' -> (mappend w' (f w), a)
 
 instance (Monoid w) => MonadBase IO (Logger w) where
   liftBase = liftIO
diff --git a/src/Language/PureScript/Make.hs b/src/Language/PureScript/Make.hs
@@ -178,8 +178,7 @@ make MakeActions{..} ms = do
   unless (null errors) $ throwError (mconcat errors)
 
   -- Bundle up all the externs and return them as an Environment
-  (warnings, externs) <- unzip . fromMaybe (internalError "make: externs were missing but no errors reported.") . sequence <$> for barriers (takeMVar . fst . snd)
-  tell (mconcat warnings)
+  (_, externs) <- unzip . fromMaybe (internalError "make: externs were missing but no errors reported.") . sequence <$> for barriers (takeMVar . fst . snd)
   return $ foldl' (flip applyExternsFileToEnvironment) initEnvironment externs
 
   where
