Ross Paterson
With version numbers, it suffices that each author has a rule of incrementing at a certain level if compatibility is broken. It need not be the same level for different packages (though that would be less confusing).
They might have two levels of compatibility: merely adding functions, types or classes will not break any clients that use explicit imports.
Yes, good point. In fact, I didn't think of the fact that adding functions etc. can also break an importer. :/ It might indeed be a good idea to be able to distinguish these two levels. Already requiring old versions when just an export is added might not offer much benefit to treating all versions incompatible to each other in the first place... Actually, upon pondering the fact that it's impossible to enforce the usage of a particular numbering scheme, it occured to me: We could just make version numbers following the standard scheme (whichever exactly) syntactically distinguishable from the current form. Then cabal-install could work happily with its new information and we don't have to /impose/ a mandatory scheme on everyone. (We could, however, apply some leverage towards "persuading" authors to use the new scheme by emitting a warning from Cabal when it's not used.) Is this a good idea? Suggestions for what "standard-scheme" version numbers could look like? (Coolest look wins!) Regards, Sven