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Latest commit 2cf3cac @simonpj simonpj Allow foralls in instance decls
This patch finally makes it possible to have explicit
foralls in an instance decl
   instance forall (a :: *). Eq a => Eq [a] where ...

This is useful to allow kind signatures or indeed
explicicit kind for-alls; see Trac #11519

I thought it would be really easy, because an instance
declaration already contains an actual HsSigType, so all
the syntactic baggage is there.  But in fact it turned
out that instance declarations were kind-checked a
little differently, because the body kind of the forall
is 'Constraint' rather than '*'.

So I fixed that.  There a slight kludge
(see Note [Body kind of a HsQualTy], but it's still a
significant improvement.

I also did the usual other round of refactoring,
improved a few error messages, tidied up comments etc.
The only significant aspect of all that was

  * Kill mkNakedSpecSigmaTy, mkNakedPhiTy, mkNakedFunTy
    These function names suggest that they do something
    complicated, but acutally they do nothing. So I
    killed them.

  * Swap the arg order of mkNamedBinder, just so that it is
    convenient to say 'map (mkNamedBinder Invisible) tvs'

  * I had to improve isPredTy, to deal with (illegal)
    types like
       (Eq a => Eq [a]) => blah
    See Note [isPeredTy complications] in Type.hs

Still to come: user manual documentation for the
instance-decl change.
Failed to load latest commit information.
.arc-linters linters/check-cpp: Don't produce debug log
bindisttest Testsuite: suggest quoting $(TEST_HC)
compiler Allow foralls in instance decls
distrib mkDocs: Fix fallout from c5f4f95
docs rts: drop unused 'traverseAllRetainerSet'
driver Fall back on ghc-stage2 when using Windows' GHCi driver
ghc ghci: fix trac issue #11481
includes Ensure that we don't produce code for pre-ARMv7 without barriers
inplace Testsuite: suggest quoting $(TEST_HC)
iserv Allow all RTS options to iserv
libffi-tarballs @ ec37a68 Update libffi-tarballs submodule to libffi 3.1 (re #10238)
libffi Update libffi-tarballs submodule to libffi 3.1 (re #10238)
libraries Fix haddocks for TypeError
mk validate: enable -DDEBUG in stage 1 by default
nofib @ a599585 Update nofib submodule again
rts rts: mark 'shutdownCapability' as static
rules Switch from -this-package-key to -this-unit-id.
testsuite Allow foralls in instance decls
utils Bump haddock submodule
.arcconfig Temporarily disable external-json linters
.arclint Temporarily disable external-json linters
.gitignore Enable RemoteGHCi on Windows
.gitmodules Revert .gitmodules changes from 6746549
.mailmap Update .mailmap [skip ci]
.travis.yml travis: use GHC 7.10.3
ANNOUNCE ANNOUNCE: Mention powerpc code generator Make configure error out on missing ghc-tarballs on Windows Mention -j and other wibbles
LICENSE Reorganisation of the source tree Build system: implement `make install-strip` (#1851)
Makefile Build system: fix 'make install-strip' in bindist Revert changes from 6746549
Vagrantfile vagrant: move files around
aclocal.m4 Ensure that we don't produce code for pre-ARMv7 without barriers
boot Synchronise ghci-package version with ghc-package
config.guess Update config.{guess,sub} to GNU automake 1.14.1
config.sub Update config.{guess,sub} to GNU automake 1.14.1 Switch from -this-package-key to -this-unit-id. Enable RemoteGHCi on Windows
install-sh Update aux files `config.{guess,sub}` and `install-sh`
packages Remove all references to sync-all LlvmCodeGen cross-compiling fixes (#9895)
validate validate: Use gz compression during bindist check

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

    $ git clone --recursive git://

    Note: cloning GHC from Github requires a special setup. See Getting a GHC repository from Github.

    DO NOT submit pull request directly to the github repo. See the GHC team's working conventions re how to contribute a patch to GHC.

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 Sphinx and Xelatex (only for PDF output).

Quick start: the following gives you a default build:

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

On Windows, you need an extra repository containing some build tools. These can be downloaded for you by configure. This only needs to be done once by running:

$ ./configure --enable-tarballs-autodownload

(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 ./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.

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!

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