On Sat, Aug 25, 2012 at 6:56 AM, Chris Moline
Hi, so with all the furor over dependency hell I've been thinking about how to address the issue. I've come up with an approach that I'm willing to try to implement, if it's sensible.
I'd like to elaborate on what I said. A goal of mine is to have every package using the most recent versions of their dependencies. I have a script whose basic functionality is mostly finished. What it does is fetch the latest version of a package, then update its build dependencies to use the most recent versions and then compile, failing if there are errors or warnings. If the build fails the most recent copy of the source code is obtained using the relevant version control command and I tinker with it trying to get it to compile. If it's too difficult I stick it in the ignore list, otherwise I generate a patch and submit it. This shouldn't take too long because most errors and warnings are trivial, for example using mkTyCon3 instead of mkTyCon or importing catch from the right module. After I make my first pass through the archive I will have a utility that follows the rss feed and recompiles all packages that depend on the new package. At this time I will start running any test suites these packages have and then running hlint on them. I imagine fixing all the hlint suggestions will take a long time. So I'm thinking the install strategy for cabal-install could simply be install the latest versions of the dependencies. Previously installed packages could continue to use the older versions of dependencies they were compiled against. We could track whether a package was installed by the user or automatically as a dependency, that way we could have an update commmand that will install the latest versions of any out-of-date packages and any automatically installed packages that are no longer depended on could then be removed. So between this script of mine, adapting packages to use explict versions of libraries and executables, and hard constraints to inhbit buggy interactions we should be able to have a nice experience with cabal-install.