ParamSpec + Concatenate + higher-order function wrapper

paramspec_wrapper.py

# See https://julien.danjou.info/p/the-hidden-cost-of-badly-typed-python
# Simple version (hardcoded types)

from collections.abc import Callable
from typing import Any, Concatenate, ParamSpec

P = ParamSpec("P")


def send_request(client: "HttpClient", method: str = "GET", timeout: int = 5) -> str:
    return f"Request sent to {client.url} with method {method} and timeout {timeout}s"


class HttpClient:
    def __init__(self, url: str):
        self.url = url


def _make_request(f: Callable[Concatenate[HttpClient, P], str]) -> Callable[Concatenate[str, P], str]:
    def g(url: str, *args: Any, **kwargs: Any) -> str:
        return f(HttpClient(url), *args, **kwargs)

    return g


make_request = _make_request(send_request)

paramspec_wrapper_generic.py

# See https://julien.danjou.info/p/the-hidden-cost-of-badly-typed-python
# Generic version

from collections.abc import Callable
from typing import Any, Concatenate


def send_request(client: "HttpClient", method: str = "GET", timeout: int = 5) -> str:
    return f"Request sent to {client.url} with method {method} and timeout {timeout}s"


class HttpClient:
    def __init__(self, url: str):
        self.url = url


def _replace_first_arg[**P, Tin, Tout, Tres](
    wrapped: Callable[Concatenate[Tout, P], Tres],
    project: Callable[[Tin], Tout],
) -> Callable[Concatenate[Tin, P], Tres]:
    def wrapper(a: Tin, *args: Any, **kwargs: Any) -> Tres:
        return wrapped(project(a), *args, **kwargs)

    return wrapper


make_request = _replace_first_arg(send_request, HttpClient)

It works with both pyright and mypy: