jorenham

import itertools, typing

def primes(n: int, /) -> typing.Generator[int]:
    yield next(sieve := itertools.count(prime := 2))
    for _ in range(n):
        yield (prime := next(sieve := filter(prime.__rmod__, sieve)))

jorenham

Without scipy-stubs	With scipy-stubs

• VSCode 1.96.2
• PyLance 2024.12.100
• pyright == 1.1.391
• scipy == 1.15.0

jorenham

original post: scipy/scipy-stubs#153 (comment)

---

Annotating a function whose return type depends on an optional positional- or keyword-only parameter in Python

Overloads are roughly similar to pattern matching[^1], but from the perspective of the caller.

Consider this function for example

jorenham

import subprocess
from pathlib import Path

# see https://github.com/astral-sh/ruff/pull/18224
from ruff.__main__ import (  # type: ignore[import-untyped]  # pyright: ignore[reportMissingTypeStubs]
    find_ruff_bin,  # noqa: PLC2701
)


def ruff_format(source: str) -> str:

jorenham

trait Family {
    type Member<T>;
}

trait Functor<A> {
    type Of: Family<Member<A> = Self>;
    fn fmap<B>(self, f: impl FnMut(A) -> B) -> <Self::Of as Family>::Member<B>;
}

//

jorenham

jorenham

{
  "label": "",
  "message": "ty",
  "logoSvg": "<svg xmlns=\"http://www.w3.org/2000/svg\" width=\"48\" height=\"48\"><path d=\"M48 7.7H27.8V0h-24v7.7H0v18.2h3.8v14.3c0 4.3 3.5 7.8 7.8 7.8H48V29.8H27.8v-3.9h12.4c4.3 0 7.8-3.5 7.8-7.8V7.7Z\" fill=\"#46ebe1\"/></svg>",
  "logoWidth": 10,
  "labelColor": "grey",
  "color": "#261230"
}

jorenham

from typing import Protocol, Literal, reveal_type


class CanRMul[InT, OutT](Protocol):
    def __rmul__(self, other: InT, /) -> OutT: ...


def twice[OutT](x: CanRMul[Literal[2], OutT]) -> OutT:
    return 2 * x