[Python] How to write type hints for recursive function computing depth in Python?

I wrote the following function in Python 3.12:

# pyright: strict

from collections.abc import Iterable, Mapping
from typing import Any

type Nested = Any | Mapping[str, Nested] | Iterable[Nested]


def _get_max_depth(obj: Nested) -> int:
if isinstance(obj, Mapping):
return max([0] + [_get_max_depth(val) for val in obj.values()]) + 1
elif isinstance(obj, Iterable) and not isinstance(obj, str):
return max([0] + [_get_max_depth(elt) for elt in obj]) + 1
else:
return 0


However, pyright 1.1.398 complains that:

demo-pyright.py
demo-pyright.py:11:42 - error: Argument type is partially unknown
Argument corresponds to parameter "obj" in function "_get_max_depth"
Argument type is "Any | Mapping[str, Any | ... | Iterable[Nested]] | Iterable[Any | Mapping[str, Nested] | ...] | Unknown" (reportUnknownArgumentType)
demo-pyright.py:11:51 - error: Type of "val" is partially unknown
Type of "val" is "Any | Mapping[str, Nested] | Iterable[Nested] | Unknown" (reportUnknownVariableType)
demo-pyright.py:13:42 - error: Argument type is partially unknown
Argument corresponds to parameter "obj" in function "_get_max_depth"
Argument type is "Unknown | Any | Mapping[str, Any | ... | Iterable[Nested]] | Iterable[Any | Mapping[str, Nested] | ...]" (reportUnknownArgumentType)
demo-pyright.py:13:51 - error: Type of "elt" is partially unknown
Type of "elt" is "Unknown | Any | Mapping[str, Nested] | Iterable[Nested]" (reportUnknownVariableType)
4 errors, 0 warnings, 0 informations


To silence pyright, I could use the following workarounds:

• Change Any to concrete types, such as int | str.
• Replace Mapping with dict.
• Replace Iterable with list.

However, I am not satisfied with these workarounds since the function should be generic.

Is there a way to write type hints that satisfy pyright in strict mode in this case?

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