Install libghc-ghc-mtl-doc by entering the following commands in the terminal:
sudo apt update sudo apt install libghc-ghc-mtl-doc
Description:
an mtl compatible version of the Ghc-Api monads; documentation
Provides an mtl compatible version of the GhcT monad-transformer defined in the GHC-API since version 6.10.1. . This package provides the documentation for a library for the Haskell programming language. See http://www.haskell.org/ for more information on Haskell.
Homepage: http://hub.darcs.net/jcpetruzza/ghc-mtl
Version: 1.2.1.0-6build4
Section: universe/doc