[Feature Request / Question] Minimum length List / Sequence

[ayroblu]

Hi I was wondering if it's possible to create a List/Sequence type with a minimum length
I work with TypeScript a lot too and here's an example TS example: https://stackoverflow.com/questions/49910889/typescript-array-with-minimum-length
(this uses some of the oddities of JavaScript to achieve this I guess)

So I'd like to have an my_list = AtLeastOneList[str] which will fail the type check on my_list[0]

Just wondering if it's possible!

[JelleZijlstra]

This isn't supported by the current type system, and I don't think there are any currently planned features that would allow it.

[ilevkivskyi]

I am keeping this open for now because theoretically we can think about overloading __getitem__() on literal values. But this is very low priority, so don't be surprised if it will be ultimately closed.

[ayroblu]

Yeah no worries, probably can pass around some opaque lists or just runtime check it in the meantime

…

On Fri, 6 Mar 2020 at 19:42, Ivan Levkivskyi ***@***.***> wrote: I am keeping this open for now because theoretically we can think about overloading __getitem__() on literal values. But this is very low priority, so don't be surprised if it will be ultimately closed. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#8501?email_source=notifications&email_token=ABFQDYQEXVMUGETOYRMXOCTRGFGZ3A5CNFSM4LC55CCKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEOCSUFA#issuecomment-595929620>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABFQDYQJSA7FY7UMC447EOLRGFGZ3ANCNFSM4LC55CCA> .

[AlexWaygood]

Similar idea to #8441

[hauntsaninja]

This would require a new type system feature, so should be discussed at https://github.com/python/typing, possibly at python/typing#786