On Sun, Nov 20, 2011 at 09:36:54PM +0100, Peter Simons wrote:
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.
I can't figure out what I'm looking at on that page, it looks like yesod fails to build. I assume that's due to zlib, since that's what you're talking about here. I assume there's a bug report upstream about the issue that would offer more useful information than a build log, or maybe a mail discussion somehwere?
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.
For us that isn't a problem, the move to 7.2 would be one-way. /M -- Magnus Therning OpenPGP: 0xAB4DFBA4 email: magnus@therning.org jabber: magnus@therning.org twitter: magthe http://therning.org/magnus Most software today is very much like an Egyptian pyramid with millions of bricks piled on top of each other, with no structural integrity, but just done by brute force and thousands of slaves. -- Alan Kay