parse strictly

This reduces memory use, because it avoids thunks that buffer parts of the
ls-tree output that are not needed.

Git/LsTree.hs

@@ -5,6 +5,8 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
+{-# LANGUAGE BangPatterns #-}
+
 module Git.LsTree (
 	TreeItem(..),
 	lsTree,
@@ -68,7 +70,7 @@ lsTreeFiles t fs repo = map parseLsTree <$> pipeNullSplitStrict ps repo
  - (The --long format is not currently supported.) -}
 parseLsTree :: String -> TreeItem
 parseLsTree l = TreeItem 
-	{ mode = fst $ Prelude.head $ readOct m
+	{ mode = smode
 	, typeobj = t
 	, sha = Ref s
 	, file = asTopFilePath $ Git.Filename.decode f
@@ -78,6 +80,8 @@ parseLsTree l = TreeItem
 	-- All fields are fixed, so we can pull them out of
 	-- specific positions in the line.
 	(m, past_m) = splitAt 7 l
-	(t, past_t) = splitAt 4 past_m
-	(s, past_s) = splitAt shaSize $ Prelude.tail past_t
-	f = Prelude.tail past_s
+	(!t, past_t) = splitAt 4 past_m
+	(!s, past_s) = splitAt shaSize $ Prelude.tail past_t
+	!f = Prelude.tail past_s
+	!smode = fst $ Prelude.head $ readOct m
+	!sfile = asTopFilePath $ Git.Filename.decode f