Rusty results

Rusty results is a Python library for dealing with result and optional types inspired by rust standard library.

Pattern matching ready!

It exposes two main types with two constructors each one.

Result

Result[T, E] is the type used for returning and propagating errors. It is based in the variants, Ok(T), representing success and containing a value, and Err(E), representing error and containing an error value.

Option

Option[T] represents an optional value: every Option is either Some(T) that contains a value, or Empty() that does not. Option types have a number of uses:

• Initial values
• Return values for functions that are not defined over the entire input range (partial function)
• Return value for otherwise reporting simple errors, where Empty is returned on error.
• Optional struct fields
• Optional function arguments

Installation

Use the package manager pip to install rusty results.

pip install rusty_results

Usage

from rusty_results import Option, Some, Empty, Result, Ok, Err, UnwrapException

Examples

"""
Example on pattern matching handling of Result
"""

from rusty_results import Result, Ok, Err


def divide(a: int, b: int) -> Result[int, str]:
    if b == 0:
        return Err("Cannot divide by zero")
    return Ok(a // b)


if __name__ == "__main__":
    values = [(10, 0), (10, 5)]
    for a, b in values:
        divide_result = divide(a, b)
        match divide_result:
            case Ok(value):
                print(f"{a} // {b} == {value}")
            case Err(e):
                print(e)

You can find more examples in the /examples folder.

Pydantic

Option and Result are fully compatible with pydantic models

import pydantic
from rusty_results import Option, Some, Empty


class MyData(pydantic.BaseModel):
    name: Option[str]
    phone: Option[int]

    
if __name__ == "__main__":
    import json
    # serialize to json
    json_data = MyData(name=Some("Link"), phone=Empty()).json()
    print(json_data)
    # deserialize json data
    data = MyData(**json.loads(json_data))
    print(data)

prints out:

{"name": {"Some": "Link"}, "phone": {}}
name=Some(Some='Link') phone=Empty()

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.

License

MIT