# Created on savesnippets.com · https://savesnippets.com/dPy8vsRwhHuv8D
from dataclasses import dataclass

@dataclass(frozen=True, slots=True)
class Ok[T]:
    value: T

@dataclass(frozen=True, slots=True)
class Err[E]:
    error: E

type Result[T, E] = Ok[T] | Err[E]

def parse_int(s: str) -> Result[int, str]:
    try:
        return Ok(int(s))
    except ValueError:
        return Err(f"Not an integer: {s!r}")

match parse_int("42"):
    case Ok(value):  print("got", value)
    case Err(error): print("failed:", error)