From 850d19d038ef7c6fb65dcd431efefd841af0132b Mon Sep 17 00:00:00 2001
From: Joey Hess <joeyh@joeyh.name>
Date: Fri, 23 Nov 2018 11:24:05 -0400
Subject: [PATCH] add dropFromEnd

---
 Git/Remote.hs        | 3 +--
 Types/Export.hs      | 3 ++-
 Utility/Scheduled.hs | 3 ++-
 Utility/Split.hs     | 4 ++++
 Utility/Url.hs       | 3 +--
 5 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/Git/Remote.hs b/Git/Remote.hs
index ce741a0d0a..28e8b0741f 100644
--- a/Git/Remote.hs
+++ b/Git/Remote.hs
@@ -26,8 +26,7 @@ isRemoteKey k = "remote." `isPrefixOf` k && ".url" `isSuffixOf` k
 
 {- Get a remote's name from the config key that specifies its location. -}
 remoteKeyToRemoteName :: String -> RemoteName
-remoteKeyToRemoteName k = intercalate "." $
-	reverse $ drop 1 $ reverse $ drop 1 $ splitc '.' k
+remoteKeyToRemoteName k = intercalate "." $ dropFromEnd 1 $ drop 1 $ splitc '.' k
 
 {- Construct a legal git remote name out of an arbitrary input string.
  -
diff --git a/Types/Export.hs b/Types/Export.hs
index 0e86f96848..35b3404240 100644
--- a/Types/Export.hs
+++ b/Types/Export.hs
@@ -16,6 +16,7 @@ module Types.Export (
 ) where
 
 import Git.FilePath
+import Utility.Split
 
 import qualified System.FilePath.Posix as Posix
 
@@ -50,4 +51,4 @@ exportDirectories (ExportLocation f) =
 	subs ps (d:ds) = (d:ps) : subs (d:ps) ds
 
 	dirs = map Posix.dropTrailingPathSeparator $
-		reverse $ drop 1 $ reverse $ Posix.splitPath f
+		dropFromEnd 1 $ Posix.splitPath f
diff --git a/Utility/Scheduled.hs b/Utility/Scheduled.hs
index b68ff901ca..12ead42521 100644
--- a/Utility/Scheduled.hs
+++ b/Utility/Scheduled.hs
@@ -30,6 +30,7 @@ import Utility.Data
 import Utility.PartialPrelude
 import Utility.Misc
 import Utility.Tuple
+import Utility.Split
 
 import Data.List
 import Data.Time.Clock
@@ -265,7 +266,7 @@ toRecurrance s = case words s of
 	constructor "month" = Just Monthly
 	constructor "year" = Just Yearly
 	constructor u
-		| "s" `isSuffixOf` u = constructor $ reverse $ drop 1 $ reverse u
+		| "s" `isSuffixOf` u = constructor $ dropFromEnd 1 u
 		| otherwise = Nothing
 	withday sd u = do
 		c <- constructor u
diff --git a/Utility/Split.hs b/Utility/Split.hs
index decfe7d396..ffea5d3f07 100644
--- a/Utility/Split.hs
+++ b/Utility/Split.hs
@@ -28,3 +28,7 @@ splitc c s = case break (== c) s of
 -- | same as Data.List.Utils.replace
 replace :: Eq a => [a] -> [a] -> [a] -> [a] 
 replace old new = intercalate new . split old
+
+-- | Only traverses the list once while dropping the last n characters.
+dropFromEnd :: Int -> [a] -> [a]
+dropFromEnd n l = zipWith const l (drop n l)
diff --git a/Utility/Url.hs b/Utility/Url.hs
index c29db74352..a9c46b4326 100644
--- a/Utility/Url.hs
+++ b/Utility/Url.hs
@@ -278,8 +278,7 @@ getUrlInfo url uo = case parseURIRelaxed url of
 contentDispositionFilename :: String -> Maybe FilePath
 contentDispositionFilename s
 	| "attachment; filename=\"" `isPrefixOf` s && "\"" `isSuffixOf` s =
-		Just $ reverse $ drop 1 $ reverse $ 
-			drop 1 $ dropWhile (/= '"') s
+		Just $ dropFromEnd 1 $ drop 1 $ dropWhile (/= '"') s
 	| otherwise = Nothing
 
 headRequest :: Request -> Request