[pypy-dev] Questions on the pypy+numpy project

David Cournapeau cournape at gmail.com
Mon Oct 17 19:20:09 CEST 2011

On Mon, Oct 17, 2011 at 2:22 PM, Michael Foord <fuzzyman at gmail.com> wrote:

> Travis' post seems to suggest that it is the responsibility of the *pypy*
> dev team to do the work necessary to integrate the numpy refactor (initially
> sponsored by Microsoft). That refactoring (smaller numpy core) seems like a
> great way forward for numpy - particularly if *it* wants to play well with
> multiple implementations, but it is unreasonable to expect the pypy team to
> pick that up!

I am pretty sure Travis did not intend to suggest that (I did not
understand that from his wordings, but maybe that's because we had
discussion in person on that topic several times already).

There are a lot of reasons to do that refactor that has nothing to do
with pypy, so the idea is more: let's talk about what pypy would need
to make this refactor beneficial for pypy *as well*. I (and other)
have advocated using more cython inside numpy and scipy. We could
share resources to do that.

> It seems odd to argue that extending numpy to pypy will be a net negative
> for the community! Sure there are some difficulties involved, just as there
> are difficulties with having multiple implementations in the first place,
> but the benefits are much greater.

The net negative would be the community split, with numpy losing some
resources taken by numpy on pypy. This seems like a plausible

Without a C numpy API, you can't have scipy or matplotlib, no
scikit-learns, etc... But you could hide most of it behind cython,
which has momentum in the scientific community. Then a realistic
approach becomes:
  - makes the cython+pypy backend a reality
  - ideally make cython to wrap fortran a reality
  - convert as much as possible from python C API to cython

People of all level can participate. The first point in particular
could help pypy besides the scipy community. And that's a plan where
both parties would benefit from each other.


> All the best,
> Michael Foord
>> Alex
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