Support async via https://github.com/aantron/promise

[Gabriel Rubens Abreu]

Also opening as a suggestion for discussing this matter

[Leeor Aharon]

Actually, this is already supported through one of the schema variations, but I'm about to remove it. I'm removing it to reduce the dependency footprint, and since I think libraries should be agnostic to these sort of frameworks. Functors provide an easy mechanism for specialising a library to the specific code base it is used in.

Have a look at #37.

[Sikan He]

This should be possible!