module Data.HandleLike (HandleLike(..), hlPutStrLn) where
import Control.Monad
import Data.Word
import qualified Data.ByteString as BS
import qualified Data.ByteString.Char8 as BSC
import System.IO
class Monad (HandleMonad h) => HandleLike h where
type HandleMonad h
hlPut :: h -> BS.ByteString -> HandleMonad h ()
hlGet :: h -> Int -> HandleMonad h BS.ByteString
hlGetByte :: h -> HandleMonad h Word8
hlGetLine :: h -> HandleMonad h BS.ByteString
hlGetContent :: h -> HandleMonad h BS.ByteString
hlClose :: h -> HandleMonad h ()
hlError :: h -> BS.ByteString -> HandleMonad h ()
hlGetByte h = do [b] <- BS.unpack `liftM` hlGet h 1; return b
hlGetLine h = do
b <- hlGetByte h
case b of
10 -> return ""
_ -> BS.cons b `liftM` hlGetLine h
hlGetContent = flip hlGet 1
hlError = hlPut
instance HandleLike Handle where
type HandleMonad Handle = IO
hlPut = BS.hPut
hlGet = BS.hGet
hlGetLine = (chopCR `liftM`) . BS.hGetLine
hlClose = hClose
hlPutStrLn :: HandleLike h => h -> BS.ByteString -> HandleMonad h ()
hlPutStrLn h = hlPut h . (`BS.append` "\n")
chopCR :: BS.ByteString -> BS.ByteString
chopCR bs
| BS.null bs = ""
| BSC.last bs == '\r' = BSC.init bs
| otherwise = bs