handling logging level

Language/Haskell/GhcMod/Logging.hs

@@ -78,6 +78,17 @@ gmLog level loc' doc = do
 
   gmlJournal (GhcModLog Nothing (Last Nothing) [(level, loc', msgDoc)])
 
+-- | Appends a collection of logs to the logging environment, with effects
+-- | if their log level specifies it should
+gmLog' :: (MonadIO m, GmLog m, GmOut m) => GhcModLog -> m ()
+gmLog' newLog@ GhcModLog { gmLogMessages } = do
+  GhcModLog { gmLogLevel = Just level' } <- gmlHistory
+  mapM_ (\(level, _, msgDoc) ->  when (level <= level') $ gmErrStrLn (docToString msgDoc)) gmLogMessages
+  -- instance Monoid GhcModLog takes the second debug level for some reason, so we need to force this to nothing
+  gmlJournal (GhcModLog Nothing (Last Nothing)  gmLogMessages)
+  where
+    docToString msgDoc = dropWhileEnd isSpace $ gmRenderDoc msgDoc
+
 gmVomit :: (MonadIO m, GmLog m, GmOut m, GmEnv m) => String -> Doc -> String -> m ()
 gmVomit filename doc content = do
   gmLog GmVomit "" $ doc <+>: text content