2.3. The layout of installed files

This section describes what files get installed where. You don't need to know it if you are simply installing GHC, but it is vital information if you are changing the implementation.

GHC is installed in two directory trees:

Library directory,

known as $(libdir), holds all the support files needed to run GHC. On Unix, this directory is usually something like /usr/lib/ghc/ghc-5.02.

Binary directory

known as $(bindir), holds executables that the user is expected to invoke. Notably, it contains ghc and ghci. On Unix, this directory can be anywhere, but is typically something like /usr/local/bin. On Windows, however, this directory must be $(libdir)/bin.

When GHC runs, it must know where its library directory is. It finds this out in one of two ways:

2.3.1. The binary directory

The binary directory, $(bindir) contains user-visible executables, notably ghc and ghci. You should add it to your $PATH

On Unix, the user-invokable ghc invokes $(libdir)/ghc-version, passing a suitable -B flag to tell ghc-version where $(libdir) is. Similarly ghci, except the extra flag --interactive is passed.

On Win32, the user-invokable ghc binary is the Real Thing (no intervening shell scripts or .bat files). Reason: we sometimes invoke GHC with very long command lines, and cmd.exe (which executes .bat files) truncates them. Similarly ghci is a C wrapper program that invokes ghc --interactive (passing on all other arguments), not a .bat file.

2.3.2. The library directory

The layout of the library directory, $(libdir) is almost identical on Windows and Unix, as follows. Differences between Windows and Unix are noted thus [Win32 only] and are commented below.

  $(libdir)/
    package.conf           GHC package configuration
    ghc-usage.txt          Message displayed by ghc ––help
    
    bin/                   [Win32 only]  User-visible binaries
         ghc.exe
         ghci.exe

    unlit                  Remove literate markup
    
    touchy.exe             [Win32 only]
    perl.exe               [Win32 only]
    gcc.exe                [Win32 only]
   
    ghc-x.xx               GHC executable [Unix only]
   
    ghc-split              Asm code splitter
    ghc-asm	           Asm code mangler

    gcc-lib/               [Win32 only] Support files for gcc
        specs              gcc configuration
 
        cpp0.exe           gcc support binaries
        as.exe
        ld.exe

        crt0.o              Standard
	   ..etc..	    binaries
        
        libmingw32.a        Standard
	   ..etc..	    libraries

        *.h                 Include files

    imports/                GHC interface files
        std/*.hi              'std' library
	lang/*.hi             'lang' library
        ..etc..

    include/                 C header files
        StgMacros.h           GHC-specific
        ..etc...              header files

        mingw/*.h            [Win32 only] Mingwin header files

    libHSrts.a              GHC library archives
    libHSstd.a
    libHSlang.a
      ..etc..

    HSstd1.o                GHC library linkables
    HSstd2.o                  (used by ghci, which does
    HSlang.o                  not grok .a files yet)

Note that:

  • $(libdir) also contains support binaries. These are not expected to be on the user's PATH, but and are invoked directly by GHC. In the Makefile system, this directory is also called $(libexecdir), but you are not free to change it. It must be the same as $(libdir).

  • We distribute gcc with the Win32 distribution of GHC, so that users don't need to install gcc, nor need to care about which version it is. All gcc's support files are kept in $(libdir)/gcc-lib/.

  • Similarly, we distribute perl and a touch replacement (touchy.exe) with the Win32 distribution of GHC.

  • The support programs ghc-split and ghc-asm are Perl scripts. The first line says #!/bin/perl; on Unix, the script is indeed invoked as a shell script, which invokes Perl; on Windows, GHC invokes $(libdir)/perl.exe directly, which treats the #!/bin/perl as a comment. Reason: on Windows we want to invoke the Perl distributed with GHC, rather than assume some installed one.