Version 23 (modified by simonpj, 9 years ago) (diff)


Layout of important files and directories

This page summarises the overall file and directory structure of GHC. We include both source files and generated files; the latter are always identified "build-tree only".

Everything starts with the main GHC repository (see Building/GettingTheSources). The build system calls that directory $(TOP). All the paths below are relative to $(TOP).

Files in $(TOP)

This script allows you to get or pull all the additional repositories that you need to build GHC. The command-line interface is documented in the file itself.
Lists the packages that darcs-all should get or pull. packages is looked at only by darcs-all.
Run validate (a shell script) before committing (see TestingPatches). The script is documented in the file itself.
Documentation files
GNU autoconf machinery
aclocal.m4, config.guess, config.sub,, install-sh,
the RPM spec file, Makefile
The top-level Makefile: see GHC Build System Architecture. GHC requires GNU make.


The libraries/ directory contains all the packages that GHC needs to build. It has one sub-directory for each package repository (e.g. base, haskell98, random). Usually each such repository builds just one package, but there is more than one in dph.

GHC's libraries are described in more detail on the libraries page.

compiler/, docs/, ghc/

These directories contain the main GHC compiler and documentation. The compiler/ directory contains the ghc package, which is linked into an executable in the ghc/ directory.

There is documentation of the intended module dependency structure of the compiler/ directory.

  • compiler/ghc.cabal: the Cabal file for GHC. If you add a module to GHC's source code, you must add it in the ghc.cabal file too, else you'll get link errors. LIES ALL LIES

The following directories appear only in the build tree:

  • compiler/stage1: generated files for the stage1 build of GHC. There are a handful of files (ghc_boot_platform.h etc), and a directory compiler/stage1/build/ that contains all the .o and .hi files for the compiler.
  • compiler/stage2: similarly stage2.

You can't run a binary from here: look in the inplace/ directory below for that.


Sources for the runtime system; see Commentary/SourceTree/Rts.


Header files for the runtime system; see Commentary/SourceTree/Includes.

utils/, libffi/

The utils directory contains support utilities that GHC uses. Some of these are themselves separate repositories that darcs-all pulls; others are part of the main GHC repository.

These utils may be built with the bootstrapping compiler, for use during the build, or with the stage1 or stage2 compiler, for installing. Some of them are built with both; we can't install the utils built with the bootstrapping compiler as they may use different versions of C libraries. The reason we use sometimes use stage2 rather than stage1 is that some utils, e.g. haddock, need the GHC API package.

  • utils/ghc-pwd is a little program we use for getting the current directory. We use this, rather than pwd, as the latter may give reults that we can't use on Windows.
  • utils/ghc-cabal is a little program we use for building the libraries. It's similar to cabal-install, but without the dependencies on http etc.

Why isn't libffi in utils/?

testsuite/, nofib/

The testsuite/ and nofib/ directories contain apparatus for testing GHC. Each is a separate repository, which can be gotten with darcs-all.


The mk/ and directories contains all the build system Makefile boilerplate; see GHC Build System Architecture. Some particular files are interesting:

  • mk/ contains Makefile settings that control your build. Details here. The file mk/ contains a starting point that you can copy to mk/ if you want.
  • mk/ this file records the fact that you are doing validation, by containing the single line Validating=YES. That in turn means the the build system gets its settings from mk/ instead of from mk/ Remove the file to stop validating.
  • mk/ just like, but applies when validating. Use this file to override the default settings for validation, which are in mk/


The inplace/ directory (build tree only) is where we "install" stage1 and stage2 compilers when they are built, and GHC's utility programs, entirely locally to the tree. The layout is exactly the same as that of an installed GHC on the host platform.

  • inplace/bin/: executables, including ghc-stage1, ghc-stage2, hasktags, hsc2hs, haddock, etc
  • inplace/lib/: suppporting libraries for the above.


Micellaneous files for building distributions.

Stuff that appears only in a build tree


  • .../dist*/ In many directories, dist* subdirectories appear. These are where Cabal puts all of the files generated while building. IS THIS STILL TRUE?