refactor

Git/UnionMerge.hs

@@ -105,20 +105,24 @@ mergeFile info file h repo = case filter (/= nullsha) [Ref asha, Ref bsha] of
 	[] -> return Nothing
 	(sha:[]) -> return $ Just $ update_index_line sha file
 	(sha:shas) -> do
-		origcontent <- L.lines <$> catObject h sha
-		content <- map L.lines <$> mapM (catObject h) shas
-		let newcontent = nub $ concat $ origcontent:content
-		newsha <- if (newcontent == origcontent)
-			then return sha
-			else hashObject (L.unlines $ newcontent) repo
+		newsha <- maybe (return sha) (hashObject repo . L.unlines) =<<
+			unionmerge
+				<$> (L.lines <$> catObject h sha)
+				<*> (map L.lines <$> mapM (catObject h) shas)
 		return $ Just $ update_index_line newsha file
 	where
 		[_colonmode, _bmode, asha, bsha, _status] = words info
 		nullsha = Ref $ replicate shaSize '0'
 
+		unionmerge origcontent content
+			| newcontent == origcontent = Nothing
+			| otherwise = Just newcontent
+			where
+				newcontent = nub $ concat $ origcontent:content
+
 {- Injects some content into git, returning its Sha. -}
-hashObject :: L.ByteString -> Repo -> IO Sha
-hashObject content repo = getSha subcmd $ do
+hashObject :: Repo -> L.ByteString -> IO Sha
+hashObject repo content = getSha subcmd $ do
 	(h, s) <- pipeWriteRead (map Param params) content repo
 	L.length s `seq` do
 		forceSuccess h