RE: [Axiom-developer] Preferred SCM

[Page, Bill]

On Tuesday, February 07, 2006 4:45 AM David Mentre wrote:
> 
> > >  darcs: I don't like its commutable patch theory
> >
> 2006/2/7, Bill Page:
>
> > What is not to like about this theory? Could you explain?
> 
> I found it seducing at first but I fear that DARCS patch
> commutation would make the understanding of merge failure
> difficult.

I have not seen any examples of this.

> In general in computer science, I don't like things which are
> not predictable.

As I understand it, the darcs "theory of patches" is motivated
by the mathematics of quantum operators -- patches are operators
on the source code tree. The properties of patches are defined
algebraically.  So, mathematically speaking I think what darcs
does is completely predictable. See:

http://www.darcs.net/manual/node8.html

In the context of the Axiom project, I like the association of
a mathematical "theory of patches" with Axiom's source code
management. Moreover, darcs is written in Haskell - a language
in the same family as Axiom's SPAD and Aldor. In principle one
could even implement darcs in Aldor.  So for me, this is mentally
a very good match.

> 
> I've also read once a post from somebody who said that DARCS
> failed on his big project and was not scalable.
>

Such information is at best anecdotal. I've done some pretty
stupid things with both CVS and arch (tla) as well. :) But I
know of no documented cases where darcs has failed when properly
applied.

I would consider Axiom at least a "medium-sized" project. So far
I have not seen any performance problems or failures on either
Unix or Windows. darcs 1.0.5 has some performance improvements -
especially on windows. Older versions on Windows required setting
a larger heap size because the Axiom source distribution includes
some rather large binary files.

Of course, as Tim Daly might have said: Source code management
is now almost a religious subject - right up there beside the
old "language wars" ;) so I don't suppose that this discussion
can have much impact on the Axiom project as a whole.

Regards,
Bill Page.