Main.hs

module Main
  ( main
  ) where

import           GHC.IO.Exception
import           System.IO
import           System.IO.Error
import           System.Process.Typed

main :: IO ()
main =
  let pc = setStdin createPipe
         $ proc "ghc" ["-e", "System.IO.hClose System.IO.stdin"]
  in withProcess pc $ \p -> do
    let inn = getStdin p
    -- wait for the pipe to be closed
    _ <- waitExitCode p
    -- Use the pipe
    hPutStrLn inn "hello"
    -- Uncomment this to make things work
    -- handleResourceVanished (hClose inn)
    pure ()

handleResourceVanished :: IO a -> IO (Maybe a)
handleResourceVanished a =
  (Just <$> a) `catchIOError`
  (\e ->
     if ioeGetErrorType e == ResourceVanished
       then pure Nothing
       else ioError e)