How can I make a graphical command line in haskell/gtk2hs?

I'm trying to create my first "real program" in haskell (something that solves integrals if polynomials) but I'm completely stumped with this part of it:

I want to make something very simple a bit like GHCi:

> user input
program output
> user input
program output
> user input
program output
> 

except that my program output is images (using LaTeX to turn mathematical expressions into PNGs) - so I can't do this using System.IO. I think it will be possible with gtk2hs which I've managed to install but I can't figure out how to make this input/output dialogue.

Please show me how it's done if you have the time. Thanks a lot!