v1.5.0 - Covariance of Wrapped Types

1.5.0 - 2020-09-23

Added

• Type inference now allows covariance for Result and Option wrapped types
  • Allows a function of type Callable[[int], RuntimeError] to be applied
    via flatmap (.and_then()) to a result of type Result[int, Exception]
  • Allows e.g. any of the following to be assigned to a type of
    Result[Number, Exception]:
    • Result[int, RuntimeError]
    • Result[float, TypeError]
    • etc.
  • This makes .and_then()/.flatmap(), .map(), .map_err(), and so on
    much more convenient to use in result chains.