zephyrus 0.6.0

mod sealed {
    pub trait Sealed {}
    impl<T, E> Sealed for Result<T, E> {}
    impl<T> Sealed for Option<T> {}
}

/// Defines what items are allowed to be returned from a command function. Since a command
/// function must return a `Result<T, E>`, this trait is only implemented for that type.
pub trait Returnable: sealed::Sealed {
    type Ok;
    type Err;
}

/// Used in the [`after hook`] to determine the inner item, which is required to implement the
/// [returnable] trait.
///
/// [returnable]: self::Returnable
/// [`after hook`]: crate::hook::AfterHook
pub trait Optional: sealed::Sealed {
    type Inner;
}

impl<T, E> Returnable for Result<T, E> {
    type Ok = T;
    type Err = E;
}

impl<T> Optional for Option<T> {
    type Inner = T;
}