[darcs-users] [Haskell-cafe] helping you contribute to darcs (poll results so far)

Jeremy Shaw jeremy at n-heptane.com
Wed Aug 6 03:20:17 EDT 2008

At Wed, 6 Aug 2008 06:29:32 +0100,
Eric Y. Kow wrote:
> Dear Haskellers,

> patch theory is still not defined clearly or rigorously enough for Haskellers

Are the darcs developers familiar with these papers (available on citeseer):

 Undo Actions in Collaborative Work, Prakash & Knister 1992
 Undoing Actions in Collaborative Work: Framework and Experience, Prakash & Knister 1994

The papers describe an undo mechanism for multiuser collaborative
editing which sounds like how I imagine darcs patch theory to be (and,
they even run into the dreaded exponential merge bug and propose a

They include some formal reasoning that may be easy to adapt to darcs?

hope this helps,

> Last Friday, I had posted a message asking how the darcs community
> could a better job recruiting developers to hack on darcs.  Thanks for
> all the great responses!  I am gratified by the suggestions you have
> offered, as well as the recent uptick in community involvement.
> The responses so far fall along three themes: offering new features,
> improving code accessibility and shaking up the community:
>   Features
>    - GUI (david48, Bit Conner)
>    - splitting/merging (Luke Palmer, Ben Franksen)
>    - binary file handling (Jason Dusek)
>    - ... already does what I want (Allan Clark, Andrew Coppin)
>   Code accessibility
>    - split into libs (Neil Mitchell)
>    - unit tests! (Ashley Moran)
>    - code documentation (Lele Gaifax)
>    - patch theory docs (Apfelmus, Ferenc Wagner)
>    - inherent simplicity of model, cf git (Austin Seipp)
>   Community
>    - release announcements (Brandon Allbery, Neil Mitchell, Don Stewart)
>    - showing ways to help  (Wren Ng Thorton, Ferenc Wagner)
>    - announcing our need for help (Wren Ng Thorton)
>    - easier entry point to darcs code, à la xmonad (Petr Rockai)
>    - more active leadership (Don Stewart, Lele Gaifax)
> One thing which is clear is that the darcs team have failed to
> communicate effectively: the code is not as well-documented as it should
> be, patch theory is still not defined clearly or rigorously enough for
> Haskellers, the recent release announcements gave people the impression
> that darcs was being abandoned, and we haven't made it clear that we
> needed your help.
> We need your help
> -----------------
> Hopefully one thing is clearer after this discussion.  We definitely
> need your help!
> What we need most of all are some Haskell optimisation gurus to join
> the project, even in a minor way.  Darcs 2 offers some huge improvements
> in safety and core efficiency.  Unfortunately, these improvements are
> overshadowed by poor performance.  Paradoxically speaking, darcs 2 just
> isn't fast enough for people to notice how much faster it has gotten!
> We need somebody to comb through our code and spot the silly things
> which are making performance suffer.  Is there something too strict?
> Too lazy?  Are going about IO completely the wrong way?
> There is no patch theory needed for this!  Anybody with an eye for
> performance should be able to rip into this code and find something
> to fix.
> If you are not an optimisation guru, there are still loads of ways to
> help.  For starters, you could help us to improve our support for
> Windows, or maybe some of the ProbablyEasy bugs:
>   http://bugs.darcs.net/issue?@columns=title,id,activity,status,assignedto&@filter=topic,status&topic=6&status=-1,1,2,3,4,5,6,7
> We will communicate better
> --------------------------
> The darcs 2 release announcement was very frank, but it also painted an
> inaccurate picture of the situation.
> Here is a clearer picture: we are all still very interested in darcs and
> want to keep using it!  If you have a large repository and you cannot
> wait for us to fix performance bugs, we wish you the best with git
> (etc).  But if darcs can handle your repository, we hope you stick
> around.
> It is true that David is taking a lower profile, but this just means
> that he is not following every discussion on the mailing list or
> every new bug and feature request.  David is still receiving patches
> and reviewing them on a daily basis, providing the usual technical
> insight.  So keep sending those patches!
> That's all for now
> ------------------
> I am going to leave things here for now, despite all the interesting
> points we could still address and see where else the discussion leads.
> In my next reply, I hope to address some of the more of suggestions you
> have offered.
> Thanks again!
> -- 
> Eric Kow <http://www.nltg.brighton.ac.uk/home/Eric.Kow>
> PGP Key ID: 08AC04F9
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