darcs 2 at last!

I'm sure you've all seen David's announcement: darcs 2.0.0 is out!

what's good

In short, darcs 2.0 is safer and faster.

Particularly, the dreaded exponential-time merge bug has now been largely resolved. Let me say it more carefully: while it may still be possible to run into exponential time merges, our improvements to conflict-handling should make it considerably less common. We hope that nobody ever runs into such a situation in practice.

Other key points are improved the hashed inventory and pristine cache which darcs more robust (you no longer have to worry about third party tools like Eclipse or Unison messing things up by mucking around with darcs internals), the ssh-connection mode which speeds up SSH-issues a lot and kills the typing-your-password-ten-million-times issue dead (at most you'll have to type it in twice).

what's bad

On the one hand, darcs 2.0.0 should be much smoother and faster for most users. On the other hand, people with large repositories (e.g. GHC-sized) might find certain operations to be somewhat slower. David does not (yet) have ideas on how to make things better for such users, and is even recommending them to switch to something else. If you've got a repository of darcs' size (over 5000 patches, 6 years, 131 contributors) or smaller, you should continue using darcs, because we still think it works better: we're still the only ones around to offer deep cherry picking... something which we think would be hard to do without radically changing the way other VCSes work. If you would like to prove us wrong, please do so and we would be most grateful!

Also, taking advantage of darcs 2 will require you to upgrade your repository to the darcs-2 format (see darcs convert), which unfortunately, is not compatible with older versions of darcs. People with new repositories should definitely start using this format. People with old repositories should probably do so at the earliest convenient moment, although this means your users will have to upgrade. Please switch to the new format. It will make everybody's lives easier.

The final piece of bad news: we're going to have to shift to a lighter weight development model, something which puts less strain on David and the rest of the contributors. The consequences are that patches might get less review [one maintainer and not two], and that you'll be seeing less of David on the mailing lists. The good news in the bad news is that our lighter weight development model is now being supported by increased automation of the administrative stuff. For example, our bug tracker is now integrated with the darcs repository so that it automatically knows when a ticket has been resolved by a patch. This increased automation gives us extra rigour and more time to think about making darcs better. The only thing we need is more of us. If you want a place to hone your Haskell, Perl or C... or if you think you know a thing or two about user interfaces, please spend some time with us.

to sum up...

Have you been hesitating to try darcs out? Well, now is a good time to do so, as our killer bugs have been fixed as well as the kind of minor nuisances that get most of us. Or... are you looking for something to work on? Uncle David needs you!

[note: Thanks to David Roundy for comments on a draft of this post]