I also would love to see more discussion of this topic. There are some academic papers on functional reactive programming and so on, but now there's this huge w

I also would love to see more discussion of this topic. There are some academic papers on functional reactive programming and so on, but now there's this huge wave of frameworks for declarative UI. I've found that there's a strong convergence on goals (one-way data binding, unification of initial creation and deltas, etc), but huge diversity in the way they're implemented. And I also agree that IMGUI is one of the most interesting of these, mostly because it's very simple. You'll find makepad (mentioned in my blog post and in comments here) is fairly directly based on IMGUI ideas, but also has the ability to retain intermediate results. Also, I've been admiring the architecture of Jetpack Compose, and feel it's true to the ideals of IMGUI - you can think of it as IMGUI + "positional memoization." And yeah, it's one thing to build toys and another to build real applications. This is one reason the focus of druid is to build a font editor, as opposed to making a GUI toolkit first and hoping for adoption.