Use `Sequence` type hints in `.transform_...()` methods of `TopLevelMixin`
Author: AntyosCreated Jul 28, 2026Updated Jul 28, 2026
Labelsbugneeds-triage
What happened?
I have noticed that several methods use list type hints instead of Sequence (which is covariant). For example:
What would you like to happen instead?
All instances of list in type hints for various mixins should be replaced with Sequence (or potentially Collection, if applicable).
I think there is some level of codegen involved for the files in vegalite/v6/, so I'm not so sure where to start if I were to make a PR.
Which version of Altair are you using?
main branch
Source: vega/altair