git-annex/Utility/Env.hs
Joey Hess 51228c2306
git-annex.cabal: Add back custom-setup stanza, so cabal new-build works.
Seems I had all the work in past commits to make this build, at least on
linux. I'm actually surprised it does, without a unix dep, Utility.Env
still builds ok somehow despite using System.Posix.Env.

This commit was sponsored by Fernando Jimenez on Patreon.
2017-12-31 13:54:41 -04:00

60 lines
1.4 KiB
Haskell

{- portable environment variables
-
- Copyright 2013 Joey Hess <id@joeyh.name>
-
- License: BSD-2-clause
-}
{-# LANGUAGE CPP #-}
{-# OPTIONS_GHC -fno-warn-tabs #-}
module Utility.Env where
#ifdef mingw32_HOST_OS
import Utility.Exception
import Control.Applicative
import Data.Maybe
import Prelude
import qualified System.Environment as E
#else
import qualified System.Posix.Env as PE
#endif
getEnv :: String -> IO (Maybe String)
#ifndef mingw32_HOST_OS
getEnv = PE.getEnv
#else
getEnv = catchMaybeIO . E.getEnv
#endif
getEnvDefault :: String -> String -> IO String
#ifndef mingw32_HOST_OS
getEnvDefault = PE.getEnvDefault
#else
getEnvDefault var fallback = fromMaybe fallback <$> getEnv var
#endif
getEnvironment :: IO [(String, String)]
#ifndef mingw32_HOST_OS
getEnvironment = PE.getEnvironment
#else
getEnvironment = E.getEnvironment
#endif
{- Adds the environment variable to the input environment. If already
- present in the list, removes the old value.
-
- This does not really belong here, but Data.AssocList is for some reason
- buried inside hxt.
-}
addEntry :: Eq k => k -> v -> [(k, v)] -> [(k, v)]
addEntry k v l = ( (k,v) : ) $! delEntry k l
addEntries :: Eq k => [(k, v)] -> [(k, v)] -> [(k, v)]
addEntries = foldr (.) id . map (uncurry addEntry) . reverse
delEntry :: Eq k => k -> [(k, v)] -> [(k, v)]
delEntry _ [] = []
delEntry k (x@(k1,_) : rest)
| k == k1 = rest
| otherwise = ( x : ) $! delEntry k rest