OK, I think this discussion is pretty much dead then. We definitely
shouldn't allow math operators in identifiers, otherwise in Python 4 or 5
we couldn't introduce them as operators.
On Fri, Jun 2, 2017 at 5:10 PM, Steven D'Aprano <st...@pearwood.info> wrote:
> On Fri, Jun 02, 2017 at 04:29:16PM -0700, Guido van Rossum wrote:
>
> > Are those characters not considered Unicode letters? Maybe we could add
> > their category to the allowed set?
>
> They're not letters:
>
> py> {unicodedata.category(c) for c in '∑√∫∞'}
> {'Sm'}
>
>
> That's Symbol, Math.
>
> One problem is that the 'Sm' category includes a whole lot of
> mathematical symbols that we probably don't want in identifiers:
>
> ∴ ∣ ≈ ≒ ≝ ≫ ≮ ⊞ (plus MANY more variations on = < and > operators)
>
> including some "Confusables":
>
> ∁ ∊ ∨ ∗ ∑ etc
>
> C ε v * Σ
>
> http://www.unicode.org/reports/tr39/
>
> Of course a language can define identifiers however it likes, but I
> think it is relevant that the Unicode Consortium's default algorithm for
> determining an identifier excludes Sm.
>
> http://www.unicode.org/reports/tr31/
>
> I also disagree with Ivan that these symbols would be particularly
> useful in general, even for maths-heavy code, although I wouldn't say no
> to special casing ∞ (infinity) and maybe √ as a unary square root
> operator.
>
>
>
> --
> Steve
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--
--Guido van Rossum (python.org/~guido)
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