Signals, the push-pull based algorithm

Thanks a lot! The left column containing the text is sticky, The right column is absolute and translate on Y and depend on an intersection observer triggered by each scroll section from the left.

After wondering what the heck glitch-freedom is and learning about it, I agree with you. It seems like it deserves at least a brief explanation in an article about how signals work.

I've gone with the universal `alien-signals` package for my project (which doesn't use a frontend framework that includes signals). They show benchmarks of being by far the fastest and have strict limits on code complexity. Those limits are also supposed to avoid glitches by design, and now at least some of that is tested[1].

[1]: https://github.com/stackblitz/alien-signals/pull/39

I didn't know about Flapjax, thanks I'll check it out. Glitch-freedom is indeed a gap in this article. I focused on the signal algorithm exclusively without some implementation optimisation like batching updates; there is so much more to cover! Maybe in a next one, Thanks!

The visual examples are rather misleading:

The "2 * x" is rather - why would the reaction from a change in X display many gradual increments of 1 instead of showing the final value once? And then why does Z =Y+1 instead of +1 to Y repeats all the steps again from X? That's not how real signal frameworks work, and also not how you'd imagine they should work

Then the next cascading example: ok, if Signal is a button, not the underlying mechanism behind it, then "computed 1" is also a signal, why isn't it called that? (though intuitively you'd think the moving dots are signals, not buttons)

I wrote a whole screed here about how glitches are evil and Rx is evil for teaching people they’re normal, but then I thought about it a bit more—

The system as described isn’t actually glitchy, is it? It doesn’t eagerly run any user computations, just dirtying, and that is idempotent so the order is irrelevant. It’s also a bit useless because it only allows you to pull out values of your own initiative, not subscribe to them, but that’s fixable by notifying all subscribers after the dirtying is done, which can’t cause glitches (unless the subscribers violate the rules of the game by triggering more signals).

So now I’m confused whether all the fiddly priority-queue needlepoint is actually needed for anything but the ability to avoid recomputation when an intermediate node decides it doesn’t want to change its output despite a change in one of its inputs. I remember the priority queue being one of the biggest performance killers in Sodium, so that can’t be it, right?..

I’m also confused about whether push-pull as TFA understands it has much to do with Conal Elliott’s definition. I don’t think it does? I feel like I need to reread the paper again.

Also also, some mention of weak references would probably be warranted.