Use `returns` in testing about classes HOT 9 OPEN

from classes import typeclass
from returns.result import Result, Success, Failure

@typeclass
def result_to_str(instance) -> str:
    """This is a typeclass definition to convert Result container to str."""

@result_to_str.instance(Result.success_type)
def _result_to_str_success(instance: Result) -> str:
    return str(instance.unwrap())  # will always receive `Success` types

@result_to_str.instance(Result.failure_type)
def _result_to_str_failure(instance: Result) -> str:
    return str(instance.failure())  # will always receive `Failure` types

if __name__ == '__main__':
    result_to_str(Success('test'))
    result_to_str(Failure('test'))

from classes import typeclass
from returns.maybe import Maybe, Some, Nothing

@typeclass
def maybe_to_str(instance) -> str:
    """This is a typeclass definition to convert Maybe container to str."""

@maybe_to_str.instance(Maybe.success_type)
def _maybe_to_str(instance: Maybe) -> str:
    return str(instance.unwrap())  # will always receive `Maybe` types

@maybe_to_str.instance(Maybe.failure_type)
def _nothing_to_str(instance: Maybe) -> str:
    return str(instance)  # will always receive `Nothing`

if __name__ == '__main__':
    maybe_to_str(Some('test'))
    maybe_to_str(Nothing)