reorder repo parameters last

Many functions took the repo as their first parameter. Changing it
consistently to be the last parameter allows doing some useful things with
currying, that reduce boilerplate.

In particular, g <- gitRepo is almost never needed now, instead
use inRepo to run an IO action in the repo, and fromRepo to get
a value from the repo.

This also provides more opportunities to use monadic and applicative
combinators.

1 files changed, 28 insertions, 26 deletions

diff --git a/Git/UnionMerge.hs b/Git/UnionMerge.hs
index 859a66ca0..32966c846 100644
--- a/Git/UnionMerge.hs
+++ b/Git/UnionMerge.hs
@@ -27,24 +27,25 @@ import Git
  -
  - Should be run with a temporary index file configured by Git.useIndex.
  -}
-merge :: Repo -> String -> String -> IO ()
-merge g x y = do
-	a <- ls_tree g x
-	b <- merge_trees g x y
-	update_index g (a++b)
+merge :: String -> String -> Repo -> IO ()
+merge x y repo = do
+	a <- ls_tree x repo
+	b <- merge_trees x y repo
+	update_index repo (a++b)
 
 {- Merges a list of branches into the index. Previously staged changed in
  - the index are preserved (and participate in the merge). -}
 merge_index :: Repo -> [String] -> IO ()
-merge_index g bs = update_index g =<< concat <$> mapM (merge_tree_index g) bs
+merge_index repo bs =
+	update_index repo =<< concat <$> mapM (\b -> merge_tree_index b repo) bs
 
 {- Feeds a list into update-index. Later items in the list can override
  - earlier ones, so the list can be generated from any combination of
  - ls_tree, merge_trees, and merge_tree_index. -}
 update_index :: Repo -> [String] -> IO ()
-update_index g l = togit ["update-index", "-z", "--index-info"] (join "\0" l)
+update_index repo l = togit ["update-index", "-z", "--index-info"] (join "\0" l)
 	where
-		togit ps content = pipeWrite g (map Param ps) (L.pack content)
+		togit ps content = pipeWrite (map Param ps) (L.pack content) repo
 			>>= forceSuccess
 
 {- Generates a line suitable to be fed into update-index, to add
@@ -53,27 +54,28 @@ update_index_line :: String -> FilePath -> String
 update_index_line sha file = "100644 blob " ++ sha ++ "\t" ++ file
 
 {- Gets the contents of a tree in a format suitable for update_index. -}
-ls_tree :: Repo -> String -> IO [String]
-ls_tree g x = pipeNullSplit g $ 
-	map Param ["ls-tree", "-z", "-r", "--full-tree", x]
+ls_tree :: String -> Repo -> IO [String]
+ls_tree x = pipeNullSplit params
+	where
+		params = map Param ["ls-tree", "-z", "-r", "--full-tree", x]
 
 {- For merging two trees. -}
-merge_trees :: Repo -> String -> String -> IO [String]
-merge_trees g x y = calc_merge g $ "diff-tree":diff_opts ++ [x, y]
+merge_trees :: String -> String -> Repo -> IO [String]
+merge_trees x y = calc_merge $ "diff-tree":diff_opts ++ [x, y]
 
 {- For merging a single tree into the index. -}
-merge_tree_index :: Repo -> String -> IO [String]
-merge_tree_index g x = calc_merge g $ "diff-index":diff_opts ++ ["--cached", x]
+merge_tree_index :: String -> Repo -> IO [String]
+merge_tree_index x = calc_merge $ "diff-index":diff_opts ++ ["--cached", x]
 
 diff_opts :: [String]
 diff_opts = ["--raw", "-z", "-r", "--no-renames", "-l0"]
 
 {- Calculates how to perform a merge, using git to get a raw diff,
  - and returning a list suitable for update_index. -}
-calc_merge :: Repo -> [String] -> IO [String]
-calc_merge g differ = do
-	diff <- pipeNullSplit g $ map Param differ
-	l <- mapM (mergeFile g) (pairs diff)
+calc_merge :: [String] -> Repo -> IO [String]
+calc_merge differ repo = do
+	diff <- pipeNullSplit (map Param differ) repo
+	l <- mapM (\p -> mergeFile p repo) (pairs diff)
 	return $ catMaybes l
 	where
 		pairs [] = []
@@ -81,9 +83,9 @@ calc_merge g differ = do
 		pairs (a:b:rest) = (a,b):pairs rest
 
 {- Injects some content into git, returning its hash. -}
-hashObject :: Repo -> L.ByteString -> IO String
-hashObject repo content = getSha subcmd $ do
-	(h, s) <- pipeWriteRead repo (map Param params) content
+hashObject :: L.ByteString -> Repo -> IO String
+hashObject content repo = getSha subcmd $ do
+	(h, s) <- pipeWriteRead (map Param params) content repo
 	L.length s `seq` do
 		forceSuccess h
 		reap -- XXX unsure why this is needed
@@ -95,13 +97,13 @@ hashObject repo content = getSha subcmd $ do
 {- Given an info line from a git raw diff, and the filename, generates
  - a line suitable for update_index that union merges the two sides of the
  - diff. -}
-mergeFile :: Repo -> (String, FilePath) -> IO (Maybe String)
-mergeFile g (info, file) = case filter (/= nullsha) [asha, bsha] of
+mergeFile :: (String, FilePath) -> Repo -> IO (Maybe String)
+mergeFile (info, file) repo = case filter (/= nullsha) [asha, bsha] of
 	[] -> return Nothing
 	(sha:[]) -> return $ Just $ update_index_line sha file
 	shas -> do
-		content <- pipeRead g $ map Param ("show":shas)
-		sha <- hashObject g $ unionmerge content
+		content <- pipeRead (map Param ("show":shas)) repo
+		sha <- hashObject (unionmerge content) repo
 		return $ Just $ update_index_line sha file
 	where
 		[_colonamode, _bmode, asha, bsha, _status] = words info