On 2/14/21 2:34 PM, Guido van Rossum wrote:
On Sun, Feb 14, 2021 at 12:51 PM David Mertz <me...@gnosis.cx <mailto:me...@gnosis.cx>> wrote:

    On Sun, Feb 14, 2021, 2:53 PM Gregory P. Smith <g...@krypto.org
    <mailto:g...@krypto.org>> wrote:

        *TL;DR of my TL;DR* - Not conveying bool-ness directly in the
        return annotation is my only complaint.  A BoolTypeGuard
        spelling would alleviate that.


    This is exactly my feeling as well. In fact, I do not understand
    why it cannot simply be a parameterized Bool. That would avoid all
    confusion. Yes, it's not the technical jargon type system
    designers use... But the existing proposal moves all the mental
    effort to non-experts who may never use type checking tools.


But note that 'bool' in Python is not subclassable.


No, but this hypothetical 'Bool'--presumably added to typing.py--might well be.


Cheers,


//arry/

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