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

[Alex Gaynor]

On Mon, Oct 17, 2011 at 1:20 PM, David Cournapeau <cournape at gmail.com>wrote:

> 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
> situation.
>
> 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.
>
> cheers,
>
> David
> >
> > All the best,
> >
> > Michael Foord
> >
> >>
> >> Alex
> >>
> >> --
> >> "I disapprove of what you say, but I will defend to the death your right
> >> to say it." -- Evelyn Beatrice Hall (summarizing Voltaire)
> >> "The people's good is the highest law." -- Cicero
> >>
> >>
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> >>
> >
> >
> >
> > --
> >
> > http://www.voidspace.org.uk/
> >
> > May you do good and not evil
> > May you find forgiveness for yourself and forgive others
> >
> > May you share freely, never taking more than you give.
> > -- the sqlite blessing http://www.sqlite.org/different.html
> >
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> >
> >
>

Why can't you have scipy and friends without a C-API?  Presumabley it's all
code that either manipulates an array or calls into an existing lib to
manipulate an array.  Why can't you write pure python code to manipulate
arrays and then call into other libs via ctypes and friends?

Alex

-- 
"I disapprove of what you say, but I will defend to the death your right to
say it." -- Evelyn Beatrice Hall (summarizing Voltaire)
"The people's good is the highest law." -- Cicero
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