Darcs

Source: Wikipedia, the free encyclopedia.
Darcs
Original author(s)David Roundy
Developer(s)Guillaume Hoffmann, et al.
Initial releaseMarch 3, 2003; 21 years ago (2003-03-03)[1]
Stable release
2.16.5[2] Edit this on Wikidata / 20 February 2022; 2 years ago (20 February 2022)
Repository
Written in
Apple macOS, MS Windows
TypeVersion control
LicenseGPL-2.0-or-later
Websitedarcs.net Edit this on Wikidata

Darcs is a

Haskell enforces some properties, and randomized testing via QuickCheck verifies many others.[3] The name is a recursive acronym for Darcs Advanced Revision Control System.[4]

Model

Darcs treats patches as first-class citizens. For the user, a repository can be seen as a set of patches, where each patch is not necessarily ordered with respect to other patches, i.e. the set of patches is only a partially ordered set. In many cases patches can be independently transmitted between various repositories.

Many branching,

Git or Mercurial
can be directly done with Darcs with the usual "pull" and "push" commands. In terms of user interface, this means that Darcs has fewer commands. These commands are more interactive: one can choose more precisely which patches they want to exchange with remote repositories.

The patches of a repository are linearly ordered. Darcs automatically calculates whether patches can be reordered (an operation called commutation), and how to do it. These calculations implement a so-called "patch theory".

A Darcs patch can contain changes of the following kinds:

  • line changes,
  • file and directory creation and deletion,
  • file and directory moving,
  • word substitution (typically used in code refactoring, for instance rename all occurrences of "foo" to "bar" in a given file).

The notion of dependency between patches is defined syntactically. Intuitively, a patch B depends on another patch A if A provides the content that B modifies. This means that patches that modify different parts of the code are considered, by default, independent. To address cases when this is not desirable, Darcs enables the user to specify explicit dependencies between patches.

Since version 2.10, Darcs uses patience diff[citation needed] by default.

History

Darcs evolved out of David Roundy's efforts to design a new patch format for

Haskell version was written in Autumn 2002 and released to the public in April 2003. Darcs 2.0 was released in April 2008 and introduced a more robust repository format, as well as a new patch semantic called "darcs-2", aimed at minimizing exponential merge conflicts.[5]
The current development strategy focuses on implementing optimizations and adding new features, while maintaining the same repository format.

Shortcomings

Darcs has been criticized for its performance issues.[6][7] This includes challenges related to the merge algorithms of Darcs 1.x, which showed exponential work to merge certain conflicts. Although not resolved completely in the subsequent versions of Darcs,[8] the frequency of exponential merges did show noticeable reductions.

Bugs still remain in which merging of recursive conflicts fails.[9]

The revision control system Pijul[10] solves those complexity problems by making conflicts and their resolutions first class citizens which can commute with other changes.

See also

  • Comparison of version control software

References

  1. ^ "Changelog for darcs". Hackage. Retrieved 2018-06-24.
  2. ^ Error: Unable to display the reference properly. See the documentation for details.
  3. ^ Roundy 2005, p. 2: ‘One of the problems I had with the initial C++ darcs was that I had no unit testing code. Within two weeks of the first darcs record, I started using QuickCheck to test the patch functions, and the same day I fixed a bug that was discovered by QuickCheck. QuickCheck makes it very easy to define properties that functions must have, which are then tested with randomly generated data.’
  4. ^ Roundy, David (2008-10-21), "prefer recursive acronymn (sic) to embarrassing one", Darcs (Commit), Darcs Hub.
  5. ^ "Two", Darcs
  6. ^ Marlow, Simon (March 7, 2007), "Current status of Darcs", Darcs users (mailing list), OSUOSL.
  7. ^ Fendt, Robert (January 9, 2009), "DVCS Round-Up: One System to Rule Them All?", Developer Network, vol. 1, Linux Foundation, archived from the original on 2009-02-28.
  8. ^ "ConflictsFAQ", Wiki, Darcs.
  9. ^ "Issue 1520 Irrefutable pattern failed for pattern Data.Maybe.Just a2", Bug Tracker, Darcs.
  10. ^ Pijul web site
  • Roundy, David (2005), "Darcs: distributed version management in Haskell", Proceedings of the 2005 ACM SIGPLAN workshop on Haskell, Tallinn, Estonia, pp. 1–4,
    S2CID 13932981

External links

Wikibooks has a book on the topic of: Understanding Darcs
Retrieved from "https://en.wikipedia.org/w/index.php?title=Darcs&oldid=1218191629"
This page is based on the copyrighted Wikipedia article: Darcs. Articles is available under the CC BY-SA 3.0 license; additional terms may apply.Privacy Policy