The example above is brief due to forum limitations, so yes, it doesn’t include lifecycles or the whole implementation of a rendering loop. But the context of that comment was using one or more languages for building interactive hierarchies of widgets, and not the topic you brought up, so it didn’t even have to.
The question is, how can we not end up in a spaghetti ball? Your scripting style alone brings nothing to the table.
I would look up to something like Elm, which does answer OP's question.
It's a no-html, widget only web framework that's been going for at least 10 years.
c = new Container()
w = new Widget()
c.add(w)
w.addActionListener(
…200 bytes of a functor boilerplate…
)
Am I missing something, or maybe you meant something else?