Hi,
About two years ago we made the painful transition from using Darcs to
Mercurial for our revision control system. This was difficult, but had
to be done because it was hard to get Darcs to run everywhere, and
there were weird corner cases where Darcs would hang. Mercurial isn't
optimal but it gets the job done.
Frankly, I think we have similar problems using Python at the core of
Sage. I've been thinking very hard about how to deal with this for
nearly a year now, and have come to the conclusion that we should make
a switch from using Python at the core of Sage to Lisp. The
transition won't be easy, but it will be well worth the effort, since
in the time frame I have in mind (30 years, say) I see Lisp really
taking off, and despite its faults, anyone who has used Lisp a lot
knows that Lisp is clearly a far better language than Python in
several critical ways. The strategy for switching will go something
like this:
1. Forking: We fork clisp. We have been using clisp for several
years now in Sage, so we're very familiar with their build system.
However, they don't make regular releases, and their foreign function
interface is severely lacking, as is their Solaris support. So we're
forking, and will call the fork LispX. I've talked with Robert
Bradshaw about creating a new language called CylispX, which will be
similar to Cython but for LispX, and I'm confident we can pull this
off.
2. Porting: We have an intense sequence if "Lisp days", both
workshops and 1-day long IRC events, where we go line-by-line through
the Sage library and rewrite everything in Lisp. As we go, we'll
make sure that the rewritten code is always at least as fast as the
original code (this shouldn't be a problem, because of LispX's
extremely good profiling and dynamic optimization features). I hope
everyone here is willing to pitch in significant time to this effort.
If you're not, I would really like to know what your concerns are.
3. Polish: I estimate step 2 will take about 3 years, given the
amount of time it took to write the original Sage library, and also
the level of familiarity of most Sage developers with Lisp. Also, we
will likely run into subtle snags with SageLisp's interface for
calling C functions. But with everybody's hard work, we'll get
through this.
4. Sage-4.0: On April 1, 2012, we'll release Sage-4.0, which will be
the complete Lisp-rewritten version of Sage. We will then get to work
on porting all of the nasty C/C++/Fortran dependencies in Sage to
Lisp. We'll likely start with GMP/MPIR (we may have to fork, though I
*hope* Bill Hart will be on board), then moving onto mpfr, mpfi,
FLINT, PARI, etc. I estimate that with lots of hard work by everybody
reading this email, we can accomplish this in at most 4 years. This
will be a great contribution to mankind.
5. Finally, on April 1, 2016, we'll release Sage-5.0, the fully
Lisp-ified Sage. We will then get back to porting Sage to Windows,
Solaris, and implementing new functionality for combinatorics, linear
algebra, number theory, algebraic geometry, optimization, etc.
If anybody isn't 100% convinced that this change isn't -- in the long
run (30 years) -- well worth our effort, please respond.
-- Best Regards,
William Stein
--
William Stein
Associate Professor of Mathematics
University of Washington
http://wstein.org
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