PackagingDrafts/Haskell

Haskell Packaging Guidelines

This page documents the guidelines and conventions for packaging Haskell projects in Fedora.

GHC (Glasgow Haskell Compiler) is the current mainstream Haskell compiler. Most Haskell packages are released on Hackage and use the Cabal package system. So currently these guidelines focus on packaging for GHC using Cabal.

Spec file templates and cabal2spec

There are three types of Haskell Cabal packages: binary only (Bin), library only (Lib), and binary and library (BinLib). One template is provided for each case:

• Bin Template
• Lib Template
• BinLib Template.

cabal2spec can create .spec files based on these templates directly from a Cabal package tarball or .cabal file for any of the three cases. Using these standard packaging templates lowers the maintenance burden considerably across Fedora's Haskell packages. With a little review and editing the .spec files should then build for most Cabal packages: for example it may be necessary to specify BuildRequires for build dependencies and Requires for any runtime or non-Haskell devel dependencies. Please report any problems in bugzilla against the cabal2spec component.

Additionally cabal2spec provides the cabal2spec-diff script which allows one to quickly see how a .spec files deviates from the generated cabal2spec .spec file.

Naming

Haskell Bin and BinLib packages should follow the usual Fedora Package Naming Guidelines for base package naming: ie follow the upstream name. Examples include projects like darcs and xmonad. BinLib packages should subpackage their libraries with naming following Lib packages.

For example the xmonad BinLib package has library subpackages

• ghc-xmonad for the shared library, and
• ghc-xmonad-devel for devel files and the static library.

The names of Haskell Lib packages built for ghc are prefixed by "ghc-". For example the zlib library package is named ghc-zlib, and the QuickCheck library is named ghc-QuickCheck.

If a library is packaged for more than one Haskell compiler or interpreter, the base name should instead be prefixed with haskell, e.g. haskell-X11. Such a package would then have subpackages for each compiler and/or interpreter it is built for (e.g. ghc-X11, hugs98-X11, etc).

Package naming preserves case to follow the upstream naming conventions as closely as possible.

Headers

The macro pkg_name is used to carry the name of the upstream library package (i.e. without the Fedora "ghc-" prefix). It should be defined at the top of Lib and BinLib packages:

%global pkg_name <package>

The macros common_summary and common_description are used as the basis for Summary and Description respectively for the Lib and BinLib base and subpackages. It is recommended to define them otherwise simple generic text based on pkg_name will be used for the subpackages.

Shared and static library linking

GHC uses static libraries by default, but now also supports shared libraries. Lib and BinLib packages should provide static, shared, and profiling libraries:

• the shared library lives in the base library package,
• the static library and header files in the -devel subpackage, and
• the profiling library and headers in the -prof subpackage.

Because GHC still assumes static versions of libraries are installed they need to be in the devel subpackage and it doesn't make sense to subpackage them yet.

Executables in Bin and BinLib packages should be dynamically linked to shared libraries.

Note that executables in BinLib packages are currently staticly linked against the library contained in the package, but will be dynamically linked against other dependent libraries.

Some particular packages may do user compilation during runtime in which case they will need Requires as well as BuildRequires for their dependencies: examples include xmonad and yi which require their devel package to be present to allow users to relink their configuration or customization.

RPM Macros

The templates all have buildrequires for ghc-rpm-macros, which provides macros.ghc to assist with packaging Haskell Cabal packages.

The main commonly used macros are:

• %ghc_bin_build
• %ghc_bin_install
• %ghc_lib_build
• %ghc_lib_install
• %ghc_lib_package
• %ghc_binlib_package

They are used in the templates and explained in more detail below.

Generally the macros should just work and do the right thing, but if necessary a macro can be replaced by its expansion and then tweaked in order to get a package to build for Fedora.

Bin packages

Bin package executables are dynamically linked to shared Haskell libraries when available, but this can be overridden if necessary by defining the ghc_without_dynamic macro.

• %ghc_bin_build is used to configure and build bin packages. It runs:
  • %global debug_package %{nil}: debuginfo is disabled since ghc's output is not in DWARF format.
  • %cabal_configure: configure the package for building and dynamic linking.
  • %cabal build: builds the package.

• %ghc_bin_install is used to install bin packages. It runs:
  • %cabal_install: installs the package.
  • %ghc_strip_dynlinked: strips the dynamically linked binary.

Lib and BinLib packages

BinLib package executables are dynamically linked to other shared Haskell libraries when available, but this can be overridden if necessary by defining the ghc_without_dynamic macro.

• %ghc_lib_build is used to configure, build and generate documentation for Lib and BinLib packages. It runs:
  • %global debug_package %{nil}: debuginfo is disabled since ghc's output is not in DWARF format.
  • %cabal_configure --ghc -p: configures the package for building with ghc and profiling. Libraries should build profiling versions of their static libraries.
  • %cabal build: builds the package.
  • %cabal haddock: generates HTML library documentation from the source code.
    • If necessary (if e.g. documentation is failing to build for some reason) this can be skipped by defining without_haddock.
    • Additionally links to colored html sourcecode are also generated with hscolour, which can be disabled by defining without_hscolour.

• %ghc_lib_install is used to install Lib and BinLib packages. It runs:
  • %cabal_install: installs the package without registering it in ghc-pkg.
  • %cabal_pkg_conf: creates ghc-pkg .conf metadata file for package installation time
  • %ghc_gen_filelists: generates rpm filelists.
  • %ghc_strip_dynlinked: strips dynamically linked objects.

• %ghc_lib_package: Boilerplate macro that defines the files list for ghc-%{pkg_name}, and its devel and prof subpackages using:
  • %ghc_package_devel: defines the devel subpackage, files list, and install scripts:
    • The install scripts run %ghc_pkg_recache to refresh the ghc package cache database with .conf file data.
    • For older versions of ghc %ghc_reindex_haddock regenerates the library documentation indices at install time.
  • %ghc_package_prof: defines the prof subpackage and file list.

• %ghc_binlib_package: BinLib equivalent of %ghc_lib_package which additionally defines ghc-%{pkg_name} as a subpackage.

Directories

GHC libraries are installed under %ghcpkgdir/%{pkg_name}-%{version}:

Library documentation lives under %ghclibdocdir/%{pkg_name}-%{version}.

File lists

Filelists for shared, devel and profiling library subpackages are generated using the following macro:

%ghc_gen_filelists

It generates three filelists: ghc-%{pkg_name}.files, ghc-%{pkg_name}-devel.files, and ghc-%{pkg_name}-prof.files.

The files sections are boilerplate generated by %ghc_lib_package and %ghc_binlib_package.

If you need to add additional files (e.g. extra %doc files or datadir files say) they can simply be added by echo'ing to the appropriate ".files" list.

RPM Lint output

Because of the nature of packaging ghc libraries, there are some warning and errors generated by rpmlint that can be waived:

ghc-%{pkg_name}-prof: E: devel-dependency ghc-%{pkg_name}-devel
ghc-%{pkg_name}-prof: W: devel-file-in-non-devel-package
%{ghcpkgdir}/libHS%{pkg_name}-%{version}_p.a

ghc-%{pkg_name}-prof should be considered an extra devel package.

ghc-%{pkg_name}-prof: W: no-documentation

prof subpackages require the devel subpackage which contains devel documents and in turn require ghc-%{pkg_name} which carries the license file.

ghc-%{pkg_name}: W: spelling-error Summary(en_US) Haskell -> Gaskell, Gaitskell, Skellum

This is fixed in Fedora 15 hunspell-en.

References

• http://fedorahosted.org/cabal2spec
• http://pkgs.fedoraproject.org/gitweb/?p=ghc-rpm-macros.git
• http://pkg-haskell.alioth.debian.org/haskell-policy/ - Debian Haskell packaging policy
• Fedora OCaml Packaging Guidelines
• Fedora Haskell SIG