haskell-emacs-text.el provides nearly all haskell functions from Data.Text. It uses `haskell-emacs' to register these functions. If you haven't installed this package via melpa, then add the path to this package to your `load-path' (for example in your .emacs). Afterwards run M-x haskell-emacs-init. (Text.tails "EMACS") => ("EMACS" "MACS" "ACS" "CS" "S" "") If you want to use these functions in your library, put there the following: (require 'haskell-emacs-text) (eval-when-compile (haskell-emacs-init)) See documentation for `haskell-emacs-init' for more info.