The Haskell community has a very nice implementation-independent mechanism for building libraries and applications, called Cabal.
I spent a few hours over the past couple of days hacking on Cabal to add the ability to build RPM packages. You can fetch my darcs repository from here:
darcs get --partial http://darcs.serpentine.com/cabal-rpm
This new capability is easy to use. It adds a single new Cabal command, called rpm.
runhaskell Setup.*hs rpm
This generates a spec file, and builds source and binary RPMs.
Here’s a quick example, of trying to build the Haskell XML-RPC library:
~/src/darcs/haxr $ runghc Setup.*hs rpm
Source tarball created: dist/SOURCES/haxr-3000.0.0.tar.gz
error: Failed build dependencies:
HaXml-ghc66 >= 1.13 is needed by haxr-3000.0.0-1.i386
HaXml-ghc66 < 1.14 is needed by haxr-3000.0.0-1.i386
Setup.lhs: rpmbuild failed with status 1
The rpm command has converted the dependencies in the haxr.cabal file into build-time and runtime dependencies in the haxr.spec file that it generated, but rpmbuild can’t find the HaXml package.
Having earlier built a HaXml package using the rpm command, I can install it with the system’s rpm command.
## rpm -i haxml-ghc66-1.13.2-1.i386.rpm
Reading package info from stdin ... done.
Saving old package config file... done.
Writing new package config file... done.
The RPM’s post-install scriptlet informs GHC’s package manager about the package’s availability:
## ghc-pkg list --simple | tr ' ' '\n' | grep -i haxml
HaXml-1.13.2
Now if I try to build haxr again, it will succeed.
By default, the rpm command builds both normal and profiling-enabled libraries. It also uses Haddock to generate library documentation. It’s possible to control these behaviours from the command line.
The command also provides a --gen-spec option, which only generates a spec file. You can use this >spec file as a basis for crafting one of your own.
I’ve used the rpm command to build about a third of the packages listed in the Hackage package database, with no problems.