{-# LANGUAGE OverloadedStrings #-}

import qualified Data.ByteString as BS
import System.IO
import System.Process

main :: IO ()
main = do
  (h_read, h_write) <- createPipe
  let msg = "233"
  BS.hPut h_write msg
  hFlush h_write
  BS.hGet h_read (BS.length msg) >>= print