git-annex/Utility/Data.hs

{- utilities for simple data types
 -
 - Copyright 2013-2021 Joey Hess <id@joeyh.name>
 -
 - License: BSD-2-clause
 -}

{-# OPTIONS_GHC -fno-warn-tabs #-}

module Utility.Data (
	firstJust,
	eitherToMaybe,
) where

{- First item in the list that is not Nothing. -}
firstJust :: Eq a => [Maybe a] -> Maybe a
firstJust ms = case dropWhile (== Nothing) ms of
	[] -> Nothing
	(md:_) -> md

eitherToMaybe :: Either a b -> Maybe b
eitherToMaybe = either (const Nothing) Just
clean up some ugly code 2013-09-27 23:52:36 +00:00			`{- utilities for simple data types`
			`-`
simplify and speed up Utility.FileSystemEncoding This eliminates the distinction between decodeBS and decodeBS', encodeBS and encodeBS', etc. The old implementation truncated at NUL, and the primed versions had to do extra work to avoid that problem. The new implementation does not truncate at NUL, and is also a lot faster. (Benchmarked at 2x faster for decodeBS and 3x for encodeBS; more for the primed versions.) Note that filepath-bytestring 1.4.2.1.8 contains the same optimisation, and upgrading to it will speed up to/fromRawFilePath. AFAIK, nothing relied on the old behavior of truncating at NUL. Some code used the faster versions in places where I was sure there would not be a NUL. So this change is unlikely to break anything. Also, moved s2w8 and w82s out of the module, as they do not involve filesystem encoding really. Sponsored-by: Shae Erisson on Patreon 2021-08-11 00:45:02 +00:00			`- Copyright 2013-2021 Joey Hess <id@joeyh.name>`
clean up some ugly code 2013-09-27 23:52:36 +00:00			`-`
relicense general utility library code to BSD Omitted a couple of files what have had significant contributions from others. 2014-05-10 14:01:27 +00:00			`- License: BSD-2-clause`
clean up some ugly code 2013-09-27 23:52:36 +00:00			`-}`

disable horrible tab warning, needed in every file that Setup.hs pulls in This is certianly a cabal bug for not passing the build options in the cabal file when building Setup.hs. And, why oh why did ghc enable this warning by default? So unhappy with this choice. 2015-05-10 20:31:50 +00:00			`{-# OPTIONS_GHC -fno-warn-tabs #-}`

explict export lists Eliminated some dead code. In other cases, exported a currently unused function, since it was a logical part of the API. Of course this improves the API documentation. It may also sometimes let ghc optimize code better, since it can know a function is internal to a module. 364 modules still to go, according to git grep -E 'module [A-Za-z.]+ where' 2019-11-21 19:38:06 +00:00			`module Utility.Data (`
			`firstJust,`
			`eitherToMaybe,`
			`) where`
clean up some ugly code 2013-09-27 23:52:36 +00:00
			`{- First item in the list that is not Nothing. -}`
			`firstJust :: Eq a => [Maybe a] -> Maybe a`
			`firstJust ms = case dropWhile (== Nothing) ms of`
			`[] -> Nothing`
			`(md:_) -> md`

			`eitherToMaybe :: Either a b -> Maybe b`
			`eitherToMaybe = either (const Nothing) Just`