On 9 Jan 2022 at 02:22:31, Steven D'Aprano <st...@pearwood.info> wrote:
> On Sat, Jan 08, 2022 at 12:59:38AM +0100, jack.jan...@cwi.nl wrote:
>
> I posted this suggestion earlier in the callable type syntax discussion,
> at which point it was completely ignored. Possibly because it’s a really
> stupid idea, but let me post it again on the off chance that it isn’t a
> stupid idea but was overlooked.
>
>
> > If I can make a wild suggestion: why not create a little language
>
> > for type specifications?
>
>
> Any time we are tempted to prefix a question with "Why not ...", the
> question is backwards. The right question is, "why should we ...".
>
> Python is 30 years old and mature, with a HUGE ecosystem of users,
> libraries, tooling, etc. It is far, far easier to get changes wrong than
> to get them right, which is why we should be conservative when it comes
> to language changes (including syntax). Changes to the language are
> "default deny", not "default accept", and it is up to the proponents of
> the change to prove their case, not for opponents to disprove it.
>
I agree 100% on these principles.
As a counter-argument, in this specific case, I’d say that the Python
typing ecosystem is only ~5 years old and still evolving rapidly, so these
principles apply with less force.
I personally believe that the syntax for type annotation doesn’t have, from
the point of view of users, to be strictly Python, as long as it’s
pythonic.
I can sympathise with the idea of repurposing the regular Python syntax to
describe types, and agree that it makes easier to bootstrap tools
(typecheckers, IDEs…) but I think it has its limits in terms of
expressivity, first.
Second, I think willing to keep the same syntax constructs for the sake of
lowering the cognitive burden of new developers is a red herring. These are
two different languages, with entirely different semantics, and the links
between them is not complement intuitive.
As an example (just for the sake of argument, I’m not proposing this kind
of change) one could argue that 'list[int]’ doesn’t really relate to how
lists are constructed or how the bracket operator is used in regular
Python. A more intuitive construct (from this point of view) could have
been ‘[int…]’. Same for dictionaries: ‘dict[int, str]’ vs. ‘{int: str}’
which looks closer that how dictionaries are constructed in Python.
S.
--
Stefane Fermigier - http://fermigier.com/ - http://twitter.com/sfermigier -
http://linkedin.com/in/sfermigier
Founder & CEO, Abilian - Enterprise Social Software -
http://www.abilian.com/
Co-Founder & Co-Chairman, National Council for Free & Open Source Software
(CNLL) - http://cnll.fr/
Co-Founder & Chairman, Association Professionnelle Européenne du Logiciel
Libre (APELL) - https://www.apell.info/
Co-Founder & Spokesperson, European Cloud Industrial Alliance (EUCLIDIA) -
https://www.euclidia.eu/
Founder, PyParis & PyData Paris - http://pyparis.org/ & http://pydata.fr/
_______________________________________________
Python-Dev mailing list -- python-dev@python.org
To unsubscribe send an email to python-dev-le...@python.org
https://mail.python.org/mailman3/lists/python-dev.python.org/
Message archived at
https://mail.python.org/archives/list/python-dev@python.org/message/V3T7JISJOSXUDBB3XZJLPG4FBZQTBSUY/
Code of Conduct: http://python.org/psf/codeofconduct/
