Bulat Ziganshin
this creates problems for developers and users. for example, program developed 3 years ago, may be easily incompatible with current ghc version
instead, i propose to keep evolving things outside of base, which will allow to use any version of any library with any ghc version. if you build something written in times of ghc 6.2 - you use old version of library. if you build something more modern - you use newer version. cabal automatically handles keeping of multiple versions of same library and using proper version for each build. this technology provides us *both* evolving of libraries and compatibility with old versions
I think it really is offtopic now, but... IMO, Cabal and hackage should treat the base as just another library and should be able to install a fresh base when required. As far as i know, this is achievable to some degree by hands. Making the base "append-only" is not a good solution, IMO.