Thank you very much!

I have built it for Fedora 20 in my Copr repo: <https://copr.fedoraproject.org/coprs/petersen/ghc-7.8/>.

(You can also install cabal-install-1.18 from <https://copr.fedoraproject.org/coprs/petersen/cabal-install/>)

We plan to add ghc-7.8 officially to Fedora 21: <https://fedoraproject.org/wiki/Changes/GHC_7.8> (wip).

Jens