The Haskell Platform specifies a very specific version set of packages, which use a 4 digit version numbering scheme. Within reason, i presume we can provide certain higher versions of these packages that are ABI compatible, but realistically, it's going to be hard to provide the latest and greatest if we have to stick to the platform. We also don't have a mechanism for delivering more than one version of the same Haskell package in fedora (yet). So the question is, how do we manage to give the user the best of both worlds?
My two cents is that we start linking a particular release of the Haskell Platform with a particular release of Fedora. The logic being is that that version of Fedora was the state of the art at the time of the release of said platform. There's also the package cabal-install.
Another option is to provide out of line repositories that automatically have the latest and greatest, but then we don't have the scripts to do that yet. Something to think about for the future.