[Python-ideas] Operator as first class citizens -- like in scala -- or yet another new operator?

[Paul Moore]

On Fri, 24 May 2019 at 09:06, Yanghao Hua <yanghao.py at gmail.com> wrote:

> Well, if python is not envisioned to be able to represent almost
> everything elegantly maybe I should indeed walk away from this idea.
> (This is sad for me ... I have been saying and believing python is
> envisioned that way for more than 20 years now).

Personally, my understanding is that Python is not designed to make
writing DSLs in Python easy (I'm a little sad about this fact myself,
but I accept that trying to make a language good at everything is
counter-productive). Features like the ability to call functions
without parentheses, user-defined operators, user-defined syntax in
general, are directly intended to make writing DSLs easier, and have
been requested and rejected many times in the past.

I believe Python is OK (I may even go as far as saying "pretty good")
for defining simple DSLs, but it's not a core goal of the language,
and you have to make your DSL fit with Python's syntax, not the other
way round.

That's not to say that features useful for DSLs aren't ever going to
be accepted, but they will need justification independent of their
value in DSLs. The matrix @ operator that you quote wasn't accepted
because "it reads well in a maths context", the proponents did a *lot*
of research to demonstrate that the operator simplified existing code,
and existing language features couldn't deliver the benefits. PEP 465
is well worth a read to give an idea of the sorts of arguments needed
to successfully introduce a new operator to Python.

Paul