Multi-threaded console apps

What's the best way to do something like an IRC client where there's messages coming from the network you'll want to display without interrupting the user's input.

I'm using a toy language (MzScheme), so I don't have easy access to some curses library or ptys or anything like that...

Any ideas, or should I just give up and write a curses wrapper?  Can GNU Readline do anything like this?

>>26
You should use STM. Is the REPL that important? Haskell's HsPlugins could provide that. Using STM would do the operations atomically, meaning you could use one input port after all.