(snip)
I would now like to add to the theoretical arguments I made then the evidence that the HSQL driver package for MySQL uses the user hooks of Cabal and I have just experienced a case of Cabal version skew breaking a build system, because this package will not build for me using Cabal 1.1.3. I am unsure at the moment if this is because my Cabal is too new or too old, and I now face the prospect of 1) hacking on the build system to match my cabal, 2) trying random cabal upgrades/downgrades or 3) pinging the package maintainers to figure out how to build this package.
You should ping the package maintainer. All Cabal releases since 1.0 have been release candidates for the exact reason that we need to experiment with the interfaces. Folks using 1.1.3 or what-have-you are early adopters who,I believe, are accepting the responsibility of helping their users when this happens. Of course I and others on this list are also happy to help. I'm very strongly leaning toward writing a compatibility layer between cabal 1.0 and 1.2 (which I hope to release soon), and I'll read up on that when I'm ready to make a release and bring up the options here. I might bug you for help :) peace, isaac