Feels like FRP. But is it isomorphic to it? I once started with a 'back of the envelope' experiment with a frp gui system and ended up with the conclusion that

Feels like FRP. But is it isomorphic to it? I once started with a 'back of the envelope' experiment with a frp gui system and ended up with the conclusion that I could not do without hierarchical state charts. So, a statechart formulation could be an 'emergent' , most simple way to formalize a Xerox Alto-descendant GUI system. The fact that they start from an existing deep GUI stack is a bit distracting to the disucssion, though...