This is an interesting concept, but it is presented so abstractly as to be opaque to even most functional programmers, I think.

The basic idea, as I understand it, is a typeclass that is more powerful than an applicative, but still less powerful than a monad, called a "selective applicative". I would summarize them like this:

* Applicative: Fixed computation graph, but no conditional structure.

* Selective applicative: Fixed computation graph with some conditional "branches".

* Monad: Dynamic computation graph and control flow, can generate new structure on the fly.

I'm sure I'm still missing a lot, but I think that's the 10,000 foot view.