Hello, I need to interact with some other program, and wrote the following code: module Main where import System.Process import System.IO main :: IO () main = do putStrLn "Running proc9..." (inp,out,err,pid) <- runInteractiveProcess "prog1" [] Nothing Nothing hSetBuffering inp LineBuffering hSetBuffering out LineBuffering hSetBuffering err LineBuffering hPutStrLn inp "1" a <- hGetLine out hPutStrLn inp a a <- hGetLine out waitForProcess pid putStrLn a But it does not work as I expected. As long as there is no need to put some input after having received some output it is no problem, but real interaction seems not possible. Is there a solution to work with the Handles as with stdin,... ? using ghc 6.6 on Windows Thanks in advance for your help.