It's sad that Cycle.js isn't getting more attention here on HN. It's truly a novel paradigm - the idea that your app is part of this loop which is entirely reactive, and that's how you communicate with the outside world.

I'm not sure this paradigm has been used elsewhere. For sure reactive programming ideas have been used in Elm and other frameworks outside the JS world, but the idea of a "reactive loop" is really game-changing to me.