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Pull request Compare This branch is 3241 commits behind ghc:master.
Latest commit 5f127fc Apr 27, 2015 @ezyang Flesh out some more Backpack examples in the merging section.
Signed-off-by: Edward Z. Yang <>
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bindisttest Follow-up to 32f41c7 Feb 26, 2014
compiler Change default roles in hs-boot files. (#9204) Apr 24, 2015
docs Flesh out some more Backpack examples in the merging section. Apr 27, 2015
driver Shorten long lines in DynFlags, add details to ghci usage guide. Nov 30, 2014
ghc Implement -f[no-]print-unicode-syntax flag for unicode syntax output … Apr 14, 2015
includes Typos in error messages and in comments Apr 10, 2015
libffi-tarballs @ b6658e5 Update libffi-tarballs submodule to libffi 3.1 (re #8701) Sep 13, 2014
libffi libffi: backport noexecstack fix for x86/win32.S Apr 2, 2015
libraries base: Export GHC.Event(.Internal).Lifetime Apr 25, 2015
nofib @ 85d10a4 update submodule Jan 28, 2015
rules Drop old integer-gmp-0.5 from GHC source tree Mar 31, 2015
testsuite Bump base version to Apr 25, 2015
utils Typos in error messages and in comments Apr 10, 2015
.arcconfig Fix .arcconfig Jun 5, 2014
.arclint Cabal submodule update: hole support and tests. Nov 27, 2014
.gitignore Ignore temporary ./configure files. Apr 7, 2015
.mailmap Add remaining <unknown>s and comments to .mailmap Nov 19, 2014
ANNOUNCE Globally replace "" with "" Oct 1, 2013 Update `sync-all` and others files w.r.t. merged testsuite (re #8545) Jan 12, 2014 docs: add to root dir (#9926) Feb 23, 2015
LICENSE Reorganisation of the source tree Apr 7, 2006 docs: Flatten MAKEHELP/SUBMAKEHELP Feb 23, 2015
Makefile build: fix 'make help' Mar 7, 2015 Explain how to clone GitHub forks. Ticket #8379. Aug 19, 2014
Vagrantfile vagrant: move files around Jul 20, 2014
aclocal.m4 Use the gold linker for aarch64/linux (#9673) Apr 21, 2015
boot Replace all #!/usr/bin/perl with #!/usr/bin/env perl Apr 30, 2014
config.guess Update config.{guess,sub} to GNU automake 1.14.1 Sep 16, 2014
config.sub Update config.{guess,sub} to GNU automake 1.14.1 Sep 16, 2014 Comments only, mostly typos Apr 3, 2015
install-sh Update aux files `config.{guess,sub}` and `install-sh` Nov 7, 2013
packages Declare official GitHub home of libraries/parallel Dec 2, 2014 LlvmCodeGen cross-compiling fixes (#9895) Dec 28, 2014
sync-all Cleanup and better documentation of sync-all script Sep 1, 2014
tarballs Add tarball syncing to darcs-all Oct 14, 2009
validate testdriver: delete unused ways Apr 7, 2015

The Glasgow Haskell Compiler

Build Status

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

For more information, visit GHC's web site.

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

Getting the Source

There are two ways to get a source tree:

  1. Download source tarballs

    Download the GHC source distribution:


    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

      $ git clone 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 GHC fork URL> ghc
      $ cd ghc
      $ ./sync-all -r git:// get

    DO NOT submit pull request directly to the github repo. See the GHC developer team's working conventions re contributing patches.

Building & Installing

For full information on building GHC, see the GHC Building Guide. 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.

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

For building library documentation, you'll need Haddock. 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, 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. 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 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 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 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. 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!