I have just pushed a new repo which packages all GHC binaries back to 8.0.1.
> nix-shell -p nur.repos.mpickering.ghc.ghc801 > ghc --version The Glorious Glasgow Haskell Compilation System, version 8.0.1
These attributes are intended to facilitate the work flow of using nix and cabal new-build together
where nix is used to provide ghc and cabal but not to manage Haskell dependencies.
It is annoying how quickly the old versions of the compiler get removed from the package set if you use this workflow but now there is an easy way to depend on whatever version of the compiler you want.
The downside to using these attributes is that there are no corresponding package sets. Only the binaries are provided.
The source can be found here