git-annex/Utility/Env.hs
Joey Hess 25703e1413
finally really add back custom-setup stanza
Fourth or fifth try at this and finally found a way to make it work.

Absurd amount of busy-work forced on me by change in cabal's behavior.
Split up Utility modules that need posix stuff out of ones used by
Setup. Various other hacks around inability for Setup to use anything
that ifdefs a use of unix.

Probably lost a full day of my life to this.
This is how build systems make their users hate them. Just saying.
2017-12-31 16:36:39 -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