[Python-Dev] PEP 465: A dedicated infix operator for matrix multiplication

[Nathaniel Smith]

On Mon, Apr 7, 2014 at 9:38 PM, Victor Stinner <victor.stinner at gmail.com> wrote:
> Hi,
>
> 2014-04-07 3:41 GMT+02:00 Nathaniel Smith <njs at pobox.com>:
>> So, I guess as far as I'm concerned, this is ready to go. Feedback welcome:
>>   http://legacy.python.org/dev/peps/pep-0465/
>
> I'm not convinced yet that there is enough usage of Python in
> mathematical world to modify the Python language to add a new
> operator. Python is used for a lot of different use cases, in a lot of
> domains. I'm not sure that it's a good thing to modify the *language*
> for a specific domain. But you can do a lot without modify the
> language :-)
>
> I'm a little bit surprised by the "Count of Python source files on
> Github matching given search terms" table, it's very different from
> these statistics:
> http://python3wos.appspot.com/
>
> Where are six, pytz,  mock, webob, etc. in your table? (all modules
> which come before "numpy" in the "Python 3 Wall of Superpowers")

They'd be down in bottom half, with ~30-50k total. (You can check
easily by running the search yourself :-).)

PyPI downloads are not a great proxy for usage, for a number of
reasons. The way to get really big on PyPI downloads is to be depended
on by a lot of projects get deployed often :-). This is very different
from being used directly in lots of different files. Consider also
that probably a majority of numpy users get numpy (and python, etc.)
by using one of the many specialized scientific python distributions
that different companies and people maintain:
  http://www.scipy.org/install.html#scientific-python-distributions
and also that using pip to install scientific packages basically never
works, so no-one uses the pip -r requirements.txt system for
deployment...

>> But isn't it weird to add an operator with no stdlib uses?
>
> I agree that it sounds weird :-) Maybe we should start by putting some
> parts of numpy/scipy/sage/pylab/panda into the stdlib? (I'm not sure
> that the new statistics module is such beginning.)

There are many reasons why this is not a great idea in the short term
-- including the problem mentioned a few sentences after the one you
quoted, which is that @ seems to be a precondition to getting
consensus on a numeric array duck type, which in turn would be a
precondition to putting an array type into the stdlib ;-). So while
putting numpy into the stdlib is probably a bad idea regardless, even
if we wanted to do it there's a chicken-and-egg problem.

> --
>
> It would be nice to support A × B too, because it's much more
> readable. You can configure a keyword to write arbitrary characters.
> For example, on Linux you can write × using "Compose x x" if you
> configured the Compose key. Or sometimes, you can replace "@" with "×"
> using your favorite text editor (copy-paste from another script, from
> a webpage, or something else).

Sounds like a pretty major violation of TOOWTDI...

-- 
Nathaniel J. Smith
Postdoctoral researcher - Informatics - University of Edinburgh
http://vorpus.org