[Haskell-beginners] How to interact with a process

[Miguel Negrao]

A 28/01/2013, às 19:36, Martin Drautzburg escreveu:

> Hello all,
> 
> I know how to play a Midi file. I also know how to read the keyboard. But I 
> don't know how to bring the two together such that I can start and stop 
> playing from the keyboard.
> 
> It is not required (just nice to have) that the console remains responsive 
> while the midi file plays. But it is essential that I can stop the 
> performance.
> 
> Is this difficult?

I’m also a beginner, so take this with a grain of salt:  I suppose the midi playing command doesn’t block until finished playing otherwise you couldn’t stop midway. If that is the case you can do something like

main =	forever readFromConsole

readFromConsole = do
	in <- getLine
	processInput in

processInput “start” = startMidi
processInput “stop” = stopMidi

where startMidi and stopMidi are functions.

best,
Miguel