You can build some lightweight dependency graphs that flush out quickly. You don’t need to describe how the signal has changed, just that it might have changed, then flush dependencies on change (some listeners might be notified of a change they don’t care about anymore) and re-register them when they come back for fresh data again.
But incremental computation isn’t exactly functional reactive programming. They are different domains in practice that often get thrown together because the problem they address can overlap. Incremental computation explicitly derives a function that can operate on deltas, FRP might just use damage and repair instead.
my understanding of FRP is the inverse of your description, I use the same definition of “functional reactive programming” as in this Jane Street blog post on the subject https://blog.janestreet.com/breaking-down-frp/ : FRP is history sensitive and wants to compute over some stream of events explicitly - and the sort of events we expect the system to handle are UI events like mouse motions, clicks, and FRP is expected to turn those into application semantics. Self-adjusting computation (like Incremental or js “signals” like alien-signals) is mostly history-insensitive by default because it’s lazy and seeks to recompute a node once during stabilize() no matter how many times an input changed since the last stabilize(). I definitely do not think “signals” in the JS/TC39 formulation of the concept is FRP: not nearly enough attention paid to first-class events.
but yeah to zoom out, the semantic boundaries and even definitions of terms in this area are kind of fuzzy and i don’t think it’s interesting to try too hard to sort stuff into a taxonomy unless you’re going to define all the parts of your taxonomy and provide a bunch of examples; these terms are not well-defined enough otherwise and arguing about ill-defined semantics is not my idea of a good time.
For example how to taxonomize something like Signia, which has fair bit of history sensitivity but is mostly concerned with diffs (https://signia.tldraw.dev/docs/incremental#using-diffs-in-co...), like Incremental uses logical clocks for validation, but is much more “pull” oriented in its recomputation/“stabilize” algorithm? To me it sounds like you’d put it in the “incremental computation” bucket because deltas; but Incremental itself doesn’t seem too concerned with deltas at the root of the library, i didn’t find any mention of them in the into docs and think it sounds more like js “signals”. https://github.com/janestreet/incremental/blob/master/src/in...