Enriching validators responses

Hi,

Thank you very much for your contribution! it is super awesome!

I'm still missing here some kind of message system, so we can know which validation rule has failed and show the correct message to the user.

Also, if result and pipe will be async we could also have async validation.

Do you have any ideas for these subjects and how to implement it with current state of the project?
Maybe implementing `Future` type? and compose each validator with a `Message` type?