Sorry I didn't get back right away, but I did answer this to someone else in a more generic context.

https://news.ycombinator.com/item?id=17008877

Ocaml folks have an awesome async library that is monadic, and I think maybe for OCaml specifically and Ocaml-specific value propositions, playing with that is better than any wall of text I can throw at you.

But: parameterizing on a generic monad is what really is the superpower they give you.