Comment by TOGoS

I've used systems that did this (some TypeScript TUI library comes to mind) and was similarly confused. I think what actually happened was that the x function/getter/whatever had some 'magic' in it that let it communicate with `Computed` as a side-effect of `Computed` computing the value.

Too magical for me. I'd rather have something like you described where inputs are explicit, so I don't have to guess about whether the magic will work in any given case.