Encode "this might fail" in the type signature instead of throwing. Python 3.12+ generics syntax keeps it compact. Forces the caller to handle the failure branch.
Python
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)Save your own code snippets
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