Please read: http://www.mew.org/~kazu/proj/ghc-mod/

The Emacs front-end is available from stable MELPA. This package should always be compatible with the latest version of ghc-mod from hackage.

To use stable stable MELPA add this to your .emacs:

(require 'package)
(add-to-list 'package-archives
	     '("melpa" . "http://melpa-stable.milkbox.net/packages/"))
(package-initialize)

With this configuration you can install the Emacs front end from MELPA (the package is called ghc there, not ghc-mod) and install the ghc-mod/ghc-modi binaries from hackage by doing:

% cabal update && cabal install ghc-mod

The easiest way to hack on ghc-mod is compile it, then add dist/build/ghc-mod and dist/build/ghc-modi to your PATH and add the elisp/ directory to your Emacs load-path.

Make sure you're not using the MELPA version of ghc.el otherwise you might get all sorts of nasty conflicts.

If you have any problems, suggestions, comments swing by #ghc-mod on Freenode.