Install libghc-extra-doc by entering the following commands in the terminal:
sudo apt update sudo apt install libghc-extra-doc
Description:
extra functions for base library; documentation
Library of extra functions for the standard Haskell libraries. Most functions are simple additions, filling out missing functionality. A few functions are available in later versions of GHC, but this package makes them available back to GHC 7.2. . This package provides the documentation for a library for the Haskell programming language. See http://www.haskell.org/ for more information on Haskell.
Homepage: https://github.com/ndmitchell/extra#readme
Version: 1.5.3-1
Section: universe/doc