[arch-haskell] Haskell's state in Arch & near future

[Peter Simons]

Hi Magnus,

 > I'm under the impression that there already are rather a lot of packages
 > that are updated to deal with changes in 7.2. I don't have any numbers on
 > that though, are there any such numbers ready available?

I am not aware of any statistics that estimate the percentage of packages
broken with GHC 7.2.x, unfortunately, but even if we'd have those kind of
statistics, the numbers might be deceptive. For instance, one of the
packages that is broken is 'zlib'. zlib itself seems to compile fine, but
the resulting package won't link when used by others. Now, that's just one
package, but the effect of that particular problem is quite significant,
because it cascades down the dependency chain. See

  http://hydra.nixos.org/job/nixpkgs/trunk/haskellPackages_ghc722.yesod

for a concrete example.

Furthermore, the problem exists the other way round, too. There are packages
that build fine with 7.2.x, but won't compile with older GHC versions, such
as 'yap' or the latest version of 'repa'. Whether that is a problem or not
depends on what you're trying to do, obviously.

Personally, I have come to prefer NixOS <http://nixos.org/> for Haskell
development, because it allows me to install any number of different GHC
versions simultaneously.

Take care,
Peter