Call julia from Python: which package?

[Chris Angelico]

On Sat, Dec 18, 2021 at 9:24 AM Oscar Benjamin
<oscar.j.benjamin at gmail.com> wrote:
> When I timed the result in Julia and in Python I found that the Julia
> code was slower than the Python code. Of course I don't know how to
> optimise Julia code so I asked one of my colleagues who does (and who
> likes to proselytise about Julia). He pointed me to here where the
> creator of Julia says "BigInts are currently pretty slow in Julia":
> https://stackoverflow.com/questions/37193586/bigints-seem-slow-in-julia#:~:text=BigInts%20are%20currently%20pretty%20slow,that%20basic%20operations%20are%20fast.
> I should make clear here that I used the gmpy2 library in Python for
> the basic integer operations which is a wrapper around the same gmp
> library that is used by Julia. That means that the basic integer
> operations were being done by the same gmp library (a C library) in
> each case. The timing differences between Python and Julia are purely
> about overhead around usage of the same underlying C library.

Point of note: "Python actually uses a hybrid approach where small
integer values are represented inline and only when values get too
large are they represented as BigInts" might be sorta-kinda true for
Python 2, but it's not true for Python 3. In all versions of CPython
to date, all integers are objects, they're not "represented inline"
(there *are* some languages that do this intrinsically, and I think
that PyPy can sometimes unbox integers, but CPython never will); and
the performance advantage of Py2's machine-sized integers clearly
wasn't worth recreating in Py3. (It would be possible to implement it
in Py3 as an optimization, while still having the same 'int' type for
both, but nobody's done it.)

So if Python's integers are faster than Julia's, it's not because
there's any sort of hybrid approach, it's simply because CPython is
more heavily optimized for that sort of work.

(That said: I have no idea whether a StackOverflow answer from 2016 is
still applicable.)

ChrisA