wai-predicates-0.1: src/Network/Wai/Predicate/Utility.hs

-- This Source Code Form is subject to the terms of the Mozilla Public
-- License, v. 2.0. If a copy of the MPL was not distributed with this
-- file, You can obtain one at http://mozilla.org/MPL/2.0/.

{-# LANGUAGE OverloadedStrings #-}

module Network.Wai.Predicate.Utility (readValues) where

import Data.ByteString (ByteString)
import Data.ByteString.From
import Data.List (foldl')
import Data.String (fromString)

readValues :: FromByteString a => [ByteString] -> Either ByteString a
readValues = foldl' res (Left "no parse") . map (runParser parser)
  where
    res (Left  _) (Right x) = Right x
    res (Right x) _         = Right x
    res _         (Left  x) = Left (fromString x)