from __future__ import annotations from typing import TypeVar import numpy as np import numpy.typing as npt T1 = TypeVar("T1", bound=npt.NBitBase) T2 = TypeVar("T2", bound=npt.NBitBase) def add(a: np.floating[T1], b: np.integer[T2]) -> np.floating[T1 | T2]: return a + b i8: np.int64 i4: np.int32 f8: np.float64 f4: np.float32 reveal_type(add(f8, i8)) # E: {float64} reveal_type(add(f4, i8)) # E: {float64} reveal_type(add(f8, i4)) # E: {float64} reveal_type(add(f4, i4)) # E: {float32}