I’m trying to use streamly-process to communicate with some GHCi instance running in the background. I came up with the following code :

import Data.Word
import qualified Streamly.Data.Stream.Prelude as Stream
import qualified Streamly.Data.Fold.Prelude as Fold
import qualified Streamly.System.Process as Process
import qualified Streamly.Console.Stdio as Stdio
import qualified Streamly.Data.Array.Foreign as Array


stringToByteArray :: String -> Array.Array Word8
stringToByteArray = Array.fromList . map (fromIntegral . fromEnum)

-- a version of getLine that does not ignore the newline character.
getNewLn :: IO String
getNewLn =  fmap (++ "n") getLine


main :: IO ()
main = do
    Stream.fold (Fold.takeEndBy ( == stringToByteArray "Leaving GHCi.") Stdio.writeChunks) $
        Process.pipeChunks "ghci" [] $
          fmap stringToByteArray $
            Stream.repeatM getNewLn
            -- When using Stream.fromList, it works ! To do so, uncomment the following :

            -- Stream.fromList ["putStrLn "This works ! "n", " 3 + 4n"

When I use fromList, it works as expected and returns :

GHCi, version 9.8.2: https://www.haskell.org/ghc/  :? for help
ghci> This works ! 
ghci> 7
ghci> Leaving GHCi.

However, when I’m using getNewLn this is what I get :

GHCi, version 9.8.2: https://www.haskell.org/ghc/  :? for help
ghci> I'm typing
the return key
several times
but nothing happens ...

What did I get wrong ?