[Haskell-cafe] darcs vs. git

Conrad Parker conrad at metadecks.org
Wed Oct 6 22:42:52 EDT 2010

(subject changed for easy filtering of flamebait, removed libraries@)

On 7 October 2010 10:45, Jason Dagit <dagit at codersbase.com> wrote:
> At the risk of starting a darcs vs. git discussion I have some
> thoughts about the tension.
> On Wed, Oct 6, 2010 at 12:10 PM, Don Stewart <dons at galois.com> wrote:
> [snip]
>> == GHC ==
>>  * ghc status
>>        + 50% split in room on moving ghc from darcs to git.
> I don't see that tension resolving itself easily.  VCS tools are
> subject to "network effects".  If your friends are using VCS Foo and
> you want to work with them, then you adopt Foo too.  It's also a part
> of the toolchain that people tend to have strong opinions about.
> One possible way to lessen the tension would be good vcs bridge tools.
>  There have been numerous repo converter projects, some even
> supporting synchronization.  There is already a git-svn tool.  Maybe
> there should be a git-darcs (and a darcs-git)?  If a git hacker out
> there wants to add darcs support to git, I'd certainly be willing to
> help them get started.
> Pushing on this a bit more, I'm fairly convinced that darcs and git
> are dual to each other in terms of underlying models.  As such, I have
> some ideas on how to unify them/convert between models.
> Unfortunately, actually having something to use is very far off as the
> ideas themselves are still immature.
> As far as I can tell, the main reasons to vote for git:
>  * Some people simply love git and want to use it for every project
>  * Git is faster and/or more memory efficient for some operations (most? all?)
>  * Github
> As far as I can tell, the main reasons to vote for darcs:
>  * GHC already uses it (inertia)
>  * The windows support appears to be more mature (I admit, this is
> somewhat subjective as neither has a spotless record here)
>  * Key players, such as the Simons, prefer the darcs UI over the git
> UI (i.e., some people prefer darcs)
>  * Darcs 2.x has consistently improved in robustness and efficiency
> over the last several years, continues to improve, and incorporates
> ideas from git.  (there is currently an experimental 'rebase' command
> in the development branch of darcs)
>  * Cherry picking
> Note: I didn't mention feature branches as a reason to prefer one over
> the other.  Both darcs and git support this.  Git uses in-repo
> branches and with darcs you can simply do a local lazy get.  Some
> people prefer one mechanism over the other, but the point is they both
> support the workflow.

I hope they do :)

With darcs, is it possible to refer to various other (local and
remote) branch names, eg. to do diffs between branches? What I mean is
that with git, I can do:

$ git fetch origin
$ git diff my-foo origin/random-bar

to see changes between my local branch "my-branch-foo" and the remote
branch "random-bar" without having to make an explicit checkout of
origin/random-bar. When the origin repo contains many branches that
other people are working on, this is a pretty neat way of keeping
track of those.

I'd really like to be able to get an overview of what branches are
available (on my local copy and remotely), like with git's various
graphing tools; I just use a "git log --graph" alias to get a tree
view in the console:


Does something similar exist for darcs?

> I would like to see the tension of darcs vs git for GHC reduced.  I
> think it ultimately amounts to: Contributors need to be able to use
> the one they prefer, instead of being forced to use the one GHC devs
> use.

I agree with that, and I don't mind switching between the two for
different projects.

Perhaps some standard subcommand aliases would go a long way to making
that easier though (log vs. changes etc.)



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