TypeIs for isinstance

Apologies if I'm missing something obvious, but I checked issues and PR's and haven't seen this mentioned explicitly.

Could isinstance use TypeIs?

With multiples checks it could return an union, with one type T a TypeIs[T].

I often find myself writing one-liner helpers functions that just call isinstance, see this script for example:

https://github.com/OutSquareCapital/pyochain/blob/master/scripts/check_docstrings.py

This both add boilerplate and a performance tax due to a double function call overhead.

I'm very often using lambdas with fluent interfaces, e.g

res = (
my_iterator
.map(lambda x: ...)
.filter(lambda x: isinstance(x, int)
)

Assuming my_iterator is an Iterator[Any], it would be fantastic if it could be narrowed to Iterator[int] without having to define a separate TypeIs function.

Commencez par l’exemple lié scripts/check_docstrings.py et le comportement demandé pour isinstance/TypeIs. Clarifiez comment les vérifications simples et multiples devraient restreindre les types, puis identifiez les stubs et les tests de typeshed nécessaires pour valider ce comportement ; le travail est terminé lorsque la proposition comporte un résultat de typage défini et la couverture correspondante.