[Nix-dev] Move to GHC 7.8.2

[Peter Simons]

Hi Oliver,

 > At work, we still can't build with GHC 7.8.2 because various
 > dependencies are still broken.

do you have a list of packages that are still causing trouble?


 >> We provide haskellPlatform_X_Y_Z attributes in all-packages.nix that
 >> install a particular version of HP -- including the corresponding
 >> GHC --, but the library choices in those packages have no effect on
 >> any of the haskellPackages_ghcXYZ.foobar packages.
 >
 > You're not really installing the platform anymore, so what's the reason
 > of calling it the platform?

Running 'nix-env -iA haskellPlatform_2013_2_0' installs exactly that --
Haskell Platform 2013.2.0. The difference to the current behavior would
be that these library versions used in that HP release have no effect on
the rest of the Nix Haskell packages: haskellPackages.HTTP would give
you the latest version of HTTP, even if the current Haskell Platform
says that we should use some older version.

This means that people who want to adhere strictly to the Haskell
Platform have to (a) configure appropriate local overrides or (b) rely
on cabal-install.

Take care,
Peter