Install libghc-x11-doc by entering the following commands in the terminal:
sudo apt update sudo apt install libghc-x11-doc
Description:
Haskell X11 binding for GHC; documentation
This library is a binding to the X11 graphics library. The binding is a direct translation of the C binding; for documentation of these calls, refer to "The Xlib Programming Manual", available online at
Homepage: https://github.com/xmonad/X11
Version: 1.8-3
Section: universe/doc