[Python-Dev] PEP 492 vs. PEP 3152, new round

[Nathaniel Smith]

On Wed, Apr 29, 2015 at 4:48 PM, Yury Selivanov <yselivanov.ml at gmail.com> wrote:
> Nathaniel,
>
> On 2015-04-29 7:35 PM, Nathaniel Smith wrote:
>>
>> What I do feel strongly about
>> is that whatever syntax we end up with, there should be*some*
>> accurate human-readable description of*what it is*. AFAICT the PEP
>> currently doesn't have that.
>
> How to define human-readable description of how unary
> minus operator works?

Hah, good question :-). Of course we all learned how to parse
arithmetic in school, so perhaps it's a bit cheating to refer to that
knowledge. Except of course basically all our users *do* have that
knowledge (or else are forced to figure it out anyway). So I would be
happy with a description of "await" that just says "it's like unary
minus but higher precedence".

Even if we put aside our trained intuitions about arithmetic, I think
it's correct to say that the way unary minus is parsed is: everything
to the right of it that has a tighter precedence gets collected up and
parsed as an expression, and then it takes that expression as its
argument. Still pretty simple.

-- 
Nathaniel J. Smith -- http://vorpus.org