Quoting Nicolas Dudebout
I would like to test the function `getScreenInfo`, but its input is a `Display` which I have no idea where to find.
You may get a Display from openDisplay: http://hackage.haskell.org/packages/archive/X11/1.6.0/doc/html/Graphics-X11-...
Is there any way to use the building blocks of XMonad in ghci for example?
It may be a bit tricky to play around with the building blocks of xmonad in ghci, because it's generally not a good idea to have two window managers running at once. However, if you really want to do this, you may at your own risk open up ghci, import XMonad, and be on your way. If you find that there are some functions you wish you had, but which are not exported by the appropriate library, you may navigate to your xmonad source directory and use ':l *XMonad' (or similar, with other module names) in ghci to bring all functions into scope. ~d