Commit d925639a authored by thoughtpolice's avatar thoughtpolice

Rewrite HACKING and convert to markdown.

Signed-off-by: thoughtpolice's avatarAustin Seipp <>
parent 7cafe18d
Getting started with hacking on GHC
So you've decided to hack on GHC, congratulations! We hope you have a
rewarding experience. This file will point you in the direction of
information to help you get started right away.
The GHC Developer's Wiki
The home for GHC Developers, with information on accessing the
latest sources, the bug tracker, and documentation on the
In particular, the wiki contains the following pages of interest to
new hackers:
Quick Start for developers
This section on the wiki will get you up and running with a
serviceable build tree in no time.
Don't skip this! By default, GHC builds with all optimizations
and profiling; most hackers will want a quicker build, so creating
a mk/ file and knowing how to rebuild only parts of GHC is
very important.
This is part of the "Building GHC" section of the wiki, which
has more detailed information on GHC's build system should you
need it.
Coding conventions
This wiki page explains the ground rules for code that is intended
to go into the mainline compiler source.
The GHC Commentary
Notes on the internals and architecture of GHC.
Mailing lists
Ask on if you have difficulties.
If you're working with the current darcs sources of GHC, then might be a more appropriate (developers hang
out here). See for
Happy Hacking! --The GHC Team
Contributing to the Glasgow Haskell Compiler
So you've decided to hack on GHC, congratulations! We hope you have a
rewarding experience. This file will point you in the direction of
information to help you get started right away.
The GHC Developer's Wiki
The home for GHC hackers is our Trac instance, located here:
From here, you can file bugs (or look them up,) use the wiki, view the
`git` history, among other things. Of particular note is the building
page, which has the high level overview of the build process and how
to get the source:
Contributing patches to GHC in a hurry
Make sure your system has the necessary tools to compile GHC. You can
find an overview here:
Next, clone the repository and all the associated libraries:
$ git clone
$ cd ghc
$ ./sync-all --testsuite get
First copy `mk/` to `mk/` and ensure it has
your preferred build settings. (You probably want to at least set
`BuildFlavour` to `quick`):
$ cp mk/ mk/
$ ... double-check mk/ ...
Now build. If you have multiple cores, **you should always use them to
speed up compilation**:
$ ./boot
$ ./configure
$ make -jN # <N> is the number of cores you have.
You can use the `./inplace/bin/ghc-stage2` binary to play with the
newly built compiler.
Now, hack on your copy and rebuild (with `make`) as necessary.
Then start by making your commits however you want. When you're done, you
can use `git format-patch` to create a series of `.patch` files you
can give to us. In this example, we'll assume I'm on a `bugfix` branch
and want to submit my patches:
$ git branch
* bugfix
$ git format-patch master -o patches
Now create a trac ticket:
And attach the files in your `patches/` directory. Set the status from
*new* to *patch* and we'll review it as soon as we can!
Useful links:
An overview of things like using git, the release process, filing bugs
and more can be located here:
You can find our coding conventions for the compiler and RTS here:
A high level overview of the bug tracker:
If you're going to contribute regularly, **learning how to use the
build system is important** and will save you lots of time. You should
read over this page carefully:
How to communicate with us
GHC is a big project, so you'll surely need help. Luckily, we can
provide plenty through a variety of means!
## IRC
If you're an IRC user, be sure to drop by the official `#ghc` channel
on [freenode]( Many (but not all) of the
developers and committers are actively there during a variety of
## Mailing lists
In the event IRC does not work or if you'd like a bigger audience, GHC
has several mailing lists for this purpose. The most important one is
[ghc-devs](, which is where
the developers actively hang out and discuss incoming changes and
There is no strict standard about where you post patches - either in
`ghc-devs` or in the bug tracker. Ideally, please put it in the bug
tracker with test cases or relevant information in a ticket, and set
the ticket status to `patch`. By doing this, we'll see the patch
quickly and be able to review. This will also ensure it doesn't get
lost. But if the change is small and self contained, feel free to
attach it to your email, and send it to `ghc-devs`.
Furthermore, if you're a developer (or want to become one!) you're
undoubtly also interested in the other mailing lists:
* [glasgow-haskell-users](
is where developers/users meet.
* [ghc-tickets](
for email from Trac.
* [ghc-builds](
for nightly build emails.
* [ghc-commits](
for commit messages when someone pushes to the repository.
El fin
Happy Hacking! -- The GHC Team
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