snekok

Small, typed tools for treating expected failures as values in Python.

from snekok.result import Err, Ok, Result


def parse_port(raw: str) -> Result[int, str]:
    if raw.isdecimal():
        return Ok(int(raw))
    return Err("port must be an integer")


port = parse_port("8080")
if isinstance(port, Err):
    print(port.error)
else:
    print(port.unwrap())

The Result API deliberately stays small: Ok, Err, Result, unwrap, unwrap_error, and the map, map_error, and_then, and and_then_async composition methods required by concrete consumers. It does not attempt to provide a functional-programming framework.

Validated scalar aliases

NonEmptySecretStr, NonEmptyStr, and NonNegativeInt are constrained nominal aliases with Pydantic support:

from pydantic import BaseModel

from snekok.types import NonEmptySecretStr, NonEmptyStr, NonNegativeInt
from snekok.validation import validate_python


class ApiSettings(BaseModel):
    api_key: NonEmptySecretStr


label = validate_python(NonEmptyStr, "hello").unwrap()
retry_count = validate_python(NonNegativeInt, 0).unwrap()
settings = ApiSettings.model_validate({"api_key": "secret-value"})
assert settings.api_key.get_secret_value() == "secret-value"

Pydantic rejects an empty value. Static type checkers also reject an ordinary SecretStr where NonEmptySecretStr is required, preventing unvalidated secrets from crossing the typed boundary.

See docs/result.md for the Result contract. Pinned design references for dmmulroy/better-result and dry-python/returns live in docs/research/.