On Mon, 2005-12-12 at 14:46 +0000, Simon Peyton-Jones wrote:
If the reason you want 6.6 is to get a new Cabal, why not download a new Cabal package? Or is there another reason you want 6.6?
That is exactly the problem. All non-trivial packages need a later version of Cabal since there are many many minor bug fixes and little feature additions in later versions of Cabal. So it's fine for package developers to download a later Cabal version but the sense some people have is that they can't ask their users to upgrade their Cabal installation from the one that comes with GHC.
Bug-fixes to 6.4 are a much smaller deal.
The improvements are a mixture of bug fixes and feature additions and some api changes. So because of the policy for minor versions of GHC is to not change any apis including those of Cabal, GHC 6.4.1 came with a version of Cabal that is widely acknowledged to be buggy and unsuitable for many packages and distributors. We can sometimes persuade users to upgrade their Cabal package separately from their GHC installation, but not always. In Gentoo we made a decision to ship Cabal-1.1.3 with GHC 6.4.1. That is after installing GHC 6.4.1 we unregister Cabal-1.0 and install Cabal-1.1.3. We do not allow any choice in that. This was necessary because our build/distribution infrastructure could not work around the bugs in Cabal-1.0 and besides many packages that we want to distribute require later versions of Cabal. So Gentoo users are ok, but other users are not. So this is why there is pressure in some quarters for a major release, (6.6) rather than another minor release (6.4.2) since the former would allow package authors to support a released version of GHC because it would come with a usable version of Cabal. A minor release with the same Cabal-1.0 would leave people in the same situation as now. I appreciate that we do not want to rush the next major release because there are new features that need to be got right. Perhaps we should think again about which Cabal version to include in the next GHC minor version, or perhaps to advise users in the release notes for GHC 6.4.2 that it is highly recommended to upgrade to Cabal version x.y. Perhaps another compromise would be for GHC 6.4.2 to ship more than one version of Cabal. It could ship version 1.0 and have that exposed by default so that GHC's api stability guarantees could be met and it could also ship a more recent version that we can agree upon so that it would be much less difficult for the average user to build packages that require more recent Cabal versions. Duncan