Happy Haskell Hacking for editors. CI: https://gitlab.com/dxld/ghc-mod/pipelines
Haskell Emacs Lisp Shell Other
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Data/Binary Cleanup some redundant constraint warnings May 22, 2016
GhcMod Fix 'debug' command when ghc(-pkg) not on PATH Jan 23, 2017
NotCPP some GHC 8.0.1 fixes May 18, 2016
System/Directory NFData fix for ClockTime on GHC 7.4 Jan 9, 2016
bench Add a criterion benchmark Jul 18, 2016
core/Language/Haskell/GhcMod Prepare for splitting off ghc-mod-core eventually Jan 12, 2017
doc Update MELPA URL Nov 1, 2015
elisp Redirect error ouput in `ghc-run-ghc-mod' Aug 8, 2016
hackage-metadata hackage-meta: Fix 5.6 dependencies Nov 1, 2016
scripts hackage-meta: update upload script Nov 1, 2016
src Prepare for splitting off ghc-mod-core eventually Jan 12, 2017
test-elisp adding test cases for elisp. Apr 23, 2014
test Prepare for splitting off ghc-mod-core eventually Jan 12, 2017
.ghci .ghci for ghci-friendliness (testing) Jan 23, 2012
.gitignore Gitingore test project stack.yaml Aug 28, 2016
.gitlab-ci.yml Add .gitlab-ci.yml Jan 16, 2017
.travis.yml [Travis] Add doctest Aug 9, 2016
COPYING.AGPL3 Change primary license to AGPL-3 Mar 3, 2015
COPYING.BSD3 Change primary license to AGPL-3 Mar 3, 2015
CodingStyle adding CodingStyle. Aug 12, 2014
GhcMod.hs Prepare for splitting off ghc-mod-core eventually Jan 12, 2017
LICENSE Add back LICENSE file pointing to COPYING.* Mar 5, 2015
README.md Minor README update [ci skip] Jan 22, 2017
Setup.hs Setup.hs: remove useless stuff Sep 7, 2016
SetupCompat.hs Setup.hs: remove useless stuff Sep 7, 2016
Utils.hs Fix upper bounds on binary for ghc<7.10 Nov 26, 2015
ghc-mod.cabal Add missing other-modules for ghc-modi Jan 23, 2017
ghcmodHappyHaskellProgram-Dg.tex Update HCAR entry Oct 29, 2015


ghc-mod: Happy Haskell Hacking

build status

ghc-mod is a couple of different things depending on what you want to do, you should read the corresponding section:


Using ghc-mod in your Development Environment

To use ghc-mod in your development environment of choice you need two things:

  • The ghc-mod program included in the package of the same name, see Installing
  • A ghc-mod frontend to integrate it into your development environment, see Frontend

Using ghc-mod as an IDE Backend Program

Directly using ghc-mod is while still supported for the time being discouraged. You should look into working with haskell-ide-engine instead.

The ghc-mod backend program is somewhat crusty and carries a lot of legacy baggage so going forward we would like to see frontends use haskell-ide-engine instead. There we're trying to get the design right from the beginning and fix the fragmentation of the Haskell Tooling Ecosystem along the way.

Using ghc-mod as a Library

Internally ghc-mod uses the Glasgow Haskell Compilers's API to implement most of it's functionality.

In order to provide a hassle free experience to users ghc-mod tries hard to automatically, and correctly, detect and if needed tweak the environment GHC needs. It also handles some of the more cumbersome parts of getting a working compiler session up and running.

This functionality can be very useful to all kinds of Haskell development tools therefore want to expose all the useful abstractions ghc-mod provides.

Right now the ghc-mod API is pretty messy a result major internal rewrites and reorganization coupled with too little time for cleanups over the course of almost 100 releases! We would like to make a cut during v6.0 or so and completely re-do the API but we need more input from downstream tool writers to do that properly, see Library API Redesign.

Right now tools like The Haskell Refactorer (HaRe) use this environment handling so they can concentrate on their core functionality instead of worrying about environments.

Most recently the haskell-ide-engine project has sprung up and if you're planning to write any kind of tool that needs editor integration eventually you should definetly look into that. haskell-ide-engine uses ghc-mod at it's core so you'll want to be familliar with it either way.

API "documentation" is here: Hackage docs.


If you have any problems, suggestions, comments swing by #ghc-mod (web client) on Freenode. If you're reporting a bug please also create an issue here so we have a way to contact you if you don't have time to stay.

Do hang around for a while if no one answers and repeat your question if you still haven't gotten any answer after a day or so. You're most likely to get an answer during the day in GMT+1.