Now that the first Haskell Platform release is out, we'll have to retool our Haskell packaging to handle it. Fun! :-\
http://www.haskell.org/haskellwiki/Haskell_Platform
The thing that's tricky is that the Platform is a combination of libraries and tools, combining the old "extralibs" GHC tarball with several libraries and tools that we already package.
Ideally, there would be some way to run "yum install ghc-platform" and have all the right things pulled in, but RPM doesn't have an apt-like notion of metapackages. I guess we could have ghc-platform be like basesystem, a package that is just a list of requires and provides.
Here would be my suggested steps.