The Glasgow Haskell Compiler
============================

[![Build Status](https://api.travis-ci.org/ghc/ghc.svg?branch=master)](http://travis-ci.org/ghc/ghc)

This is the source tree for [GHC][1], a compiler and interactive
environment for the Haskell functional programming language.

For more information, visit [GHC's web site][1].

Information for developers of GHC can be found on the [GHC Trac][2].


Getting the Source
==================

There are two ways to get a source tree:

 1. *Download source tarballs*

  Download the GHC source distribution:

        ghc-<version>-src.tar.bz2

  which contains GHC itself and the "boot" libraries.

 2. *Check out the source code from git*

  The official mirror for GHC on GitHub is located at https://github.com/ghc/ghc.

        $ git clone git://github.com/ghc/ghc.git
        $ cd ghc
        $ ./sync-all get

  If you want to clone your own fork instead, add an argument to `sync-all` to
  tell it where it can find the other repositories it needs.

        $ git clone <your preferred github.com GHC fork URL> ghc
        $ cd ghc
        $ ./sync-all -r git://github.com/ghc get

  **DO NOT submit pull request directly to the github repo.**
  *See the GHC developer team's working conventions re [contributing patches](http://ghc.haskell.org/trac/ghc/wiki/WorkingConventions/Git#Contributingpatches "ghc.haskell.org/trac/ghc/wiki/WorkingConventions/Git#Contributingpatches").*


Building & Installing
=====================

For full information on building GHC, see the [GHC Building Guide] [3].
Here follows a summary - if you get into trouble, the Building Guide
has all the answers.

Before building GHC you may need to install some other tools and
libraries.  See, [Setting up your system for building GHC] [8].

*NB.* In particular, you need [GHC] [1] installed in order to build GHC,
because the compiler is itself written in Haskell.  You also need
[Happy] [4], [Alex] [5], and [Cabal] [9].  For instructions on how
to port GHC to a new platform, see the [GHC Building Guide] [3].

For building library documentation, you'll need [Haddock] [6].  To build
the compiler documentation, you need a good DocBook XML toolchain and
dblatex.

**Quick start**: the following gives you a default build:

    $ perl boot
    $ ./configure
    $ make         # can also say 'make -jX' for X number of jobs
    $ make install

(NB: **Do you have multiple cores? Be sure to tell that to `make`!** This can
save you hours of build time depending on your system configuration, and is
almost always a win regardless of how many cores you have. As a simple rule,
you should have about N+1 jobs, where `N` is the amount of cores you have.)

The `perl boot` step is only necessary if this is a tree checked out
from git.  For source distributions downloaded from [GHC's web site] [1],
this step has already been performed.

These steps give you the default build, which includes everything
optimised and built in various ways (eg. profiling libs are built).
It can take a long time.  To customise the build, see the file `HACKING`.

Once you have a build you need to keep it going.  You need to keep all
repos in sync with the [sync-all script] [7].  To get the latest changes:

    $ ./sync-all pull
    $ ./sync-all get

Filing bugs and feature requests
================================

If you've encountered what you believe is a bug in GHC, or you'd like
to propose a feature request, please let us know! Submit a ticket in
our [bug tracker] [10] and we'll be sure to look into it. Remember:
**Filing a bug is the best way to make sure your issue isn't lost over
time**, so please feel free.

If you're an active user of GHC, you may also be interested in joining
the [glasgow-haskell-users] [11] mailing list, where developers and
GHC users discuss various topics and hang out.

Hacking & Developing GHC
========================

Once you've filed a bug, maybe you'd like to fix it yourself? That
would be great, and we'd surely love your company! If you're looking
to hack on GHC, check out the guidelines in the `HACKING.md` file in
this directory - they'll get you up to speed quickly.

Contributors & Acknowledgements
===============================

GHC in its current form wouldn't exist without the hard work of
[its many contributors] [12]. Over time, it has grown to include the
efforts and research of many institutions, highly talented people, and
groups from around the world. We'd like to thank them all, and invite
you to join!

  [1]:  http://www.haskell.org/ghc/            "www.haskell.org/ghc/"
  [2]:  http://ghc.haskell.org/trac/ghc    "ghc.haskell.org/trac/ghc"
  [3]:  http://ghc.haskell.org/trac/ghc/wiki/Building
          "ghc.haskell.org/trac/ghc/wiki/Building"
  [4]:  http://www.haskell.org/happy/          "www.haskell.org/happy/"
  [5]:  http://www.haskell.org/alex/           "www.haskell.org/alex/"
  [6]:  http://www.haskell.org/haddock/        "www.haskell.org/haddock/"
  [7]:  http://ghc.haskell.org/trac/ghc/wiki/Building/SyncAll
          "http://ghc.haskell.org/trac/ghc/wiki/Building/SyncAll"
  [8]:  http://ghc.haskell.org/trac/ghc/wiki/Building/Preparation
          "http://ghc.haskell.org/trac/ghc/wiki/Building/Preparation"
  [9]:  http://www.haskell.org/cabal/          "http://www.haskell.org/cabal/"
  [10]: http://ghc.haskell.org/trac/ghc/
          "http://ghc.haskell.org/trac/ghc/"
  [11]: http://www.haskell.org/pipermail/glasgow-haskell-users/
          "http://www.haskell.org/pipermail/glasgow-haskell-users/"
  [12]: http://ghc.haskell.org/trac/ghc/wiki/TeamGHC
          "http://ghc.haskell.org/trac/ghc/wiki/TeamGHC"