[jasim]

Just to add, I wish I was able to articulate clearly why I prefer one over the other. One way might be to contrast both OO and FP approaches with a reference UI and have discussions based on concrete code. But that's a lot of work. For now having worked with both approaches, I have a visceral preferences to express UIs as a function of state.

I'm interested in this area because I've been trying to figure out a way to express UIs visually (like thru erstwhile Delphi or VB6 forms, or today's vector drawing tools like Sketch), but unlike all existing renditions, they have to be composable, reusable, and Turing complete. This is a little more tractable than it might seem if we use Lambda Calculus rather than Turing Machines to think of the problem, and so expect the interface to be pure and side-effect free.