python functional factorial

fact.py

from functools import lru_cache
from pydantic import BaseModel
from pymonad.either import Left, Right


class Error(BaseModel):
    message: str


def curry(func):
    def curried(*args, **kwargs):
        if len(args) + len(kwargs) >= func.__code__.co_argcount:
            return func(*args, **kwargs)
        return lambda *args2, **kwargs2: curried(*(args + args2), **(kwargs | kwargs2))

    return curried


def sealed_class(name, *args, **kwargs):
    return type(name,
                (BaseModel,),
                {'__annotations__': kwargs})


EitherResult = sealed_class('EitherResult',
                            right=Right,
                            left=Left)


@lru_cache
def memoize(func):
    memo = {}

    def helper(n):
        if n not in memo:
            memo[n] = func(n)
        return memo[n]

    return helper


@curry
def fact(n):
    return (
        Right(n) if n >= 0 else
        Left(Error(message='Invalid input'))
    ).bind(lambda x:
           Right(1)
           if x == 0
           else fact(x - 1).bind(lambda y: Right(x * y)))


def run_computation(n):
    result = fact(n)
    return result.value \
        if result.is_right() \
        else Error(message=result.value.message)


def main():
    try:
        computation_result = run_computation(int(input(
            "Entrez un nombre entier pour calculer sa factorielle : "
        )))
        if isinstance(computation_result, int):
            print(f"Le résultat de la factorielle est : {computation_result}")
        elif isinstance(computation_result, Error):
            print(f"Erreur : {computation_result.message}")
        else:
            print("Une erreur inattendue s'est produite.")
    except ValueError:
        print("Erreur : Veuillez entrer un nombre entier valide.")


if __name__ == "__main__":
    main()