[xmonad] Retrieving screen resolution + ghci for XMonad

[Nicolas Dudebout]

Thank you for the pointers.
However, this is exactly an instance of my problem.
I now have some documentation and I would really like to be able to play
with the functions I see.
I would like to test the function `getScreenInfo`, but its input is a
`Display` which I have no idea where to find.

Is there any way to use the building blocks of XMonad in  ghci for example?