> I want to have a purely functional domain that I wrap in an imperative shell. Trying to model side-effects in a purely functional manner using something like applicative functors just doesn't give the productivity boost that I want.
Funtional Reactive is a very good way to create that mix. Web Front developers have realized that, and that's the reason why most modern frameworks have been veering towards this model slowly, with Promises and Observers everywhere.
When you represent state as an asynchronous stream that you process with pure functional methods, you get a straightforward model with the best of both paradigms.