tvl-depot/users/Profpatsch/arglib/ArglibNetencode.hs
Profpatsch fdc5763f5b feat(users/Profpatsch): init haskell arglib-netencode
Mirrors the rust exec-helpers

Change-Id: I96f211d6545e228b8ae0c1dce4e60e6f6867690c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6117
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>
2022-08-22 12:47:53 +00:00

25 lines
910 B
Haskell

{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes #-}
module ArglibNetencode where
import qualified Data.Attoparsec.ByteString as Atto
import Data.Maybe (fromMaybe)
import ExecHelpers
import MyPrelude
import Netencode
import qualified System.Environment as Env
import qualified System.Posix.Env.ByteString as ByteEnv
arglibNetencode :: CurrentProgramName -> Maybe Text -> IO T
arglibNetencode progName mEnvvar = do
let envvar = mEnvvar & fromMaybe "ARGLIB_NETENCODE" & textToBytesUtf8
ByteEnv.getEnv envvar >>= \case
Nothing -> dieUserError progName [fmt|could not read args, envvar {envvar} not set|]
Just bytes ->
case Atto.parseOnly (Netencode.netencodeParser <* Atto.endOfInput) bytes of
Left err -> dieEnvironmentProblem progName [fmt|arglib parsing error: {err}|]
Right t -> do
ByteEnv.unsetEnv envvar
pure t