Hi Joachim,
The Hoogle databases are expected to change very rarely - most users will install them when they install Hoogle. A small number will update them occasionally as the packages update. I'm using the Cabal datadir to store the databases, but does Cabal provide a more sensible place to put them? As a Windows user, I'm happy to defer to what Posix system users want.
shouldn’t they change with every library update? In that case, maybe that should be managed by cabal, similar to how cabal can update your haddock index at ~/.cabal/share/doc/index.html.
Yes, that's exactly how it should work. All we need is someone to do the work :-) There is a bug tracking the progress on this issue here: http://code.google.com/p/ndmitchell/issues/detail?id=80 - but its a reasonable amount of work, touching lots of different parts of the Haskell infra. Thanks, Neil