Svelte 5: Runes

Or am I missing something important?

Or have I missed something important?

Implementation-wise, this is vastly simpler than Svelte 4, because everything is explicit.

One thing we didn't really show today is how this works in your editor in practice — for example, TypeScript thinks `$state` and `$derived` are just the identity function. It makes sense when you use it, but I appreciate that I'm basically asking you to just trust me on that!

> Previously, Svelte’s reactivity model was very easy to understand, including its limitations, because it was the result of very simple analysis

I totally understand what you're saying. But in fact the analysis is _anything but_ simple — in places it's frighteningly complicated, to the point that even I sometimes don't understand what's going on! And that's part of the problem — because Svelte 4 is more implicit, you can't really know what's happening in a lot of cases, you just have to hope that the compiler knows what it's doing.

Shared-everything does not scale. It ends in whack-a-mole and an escalating blame game about whether team members are fit to work on the project. It’s bunk. It’s deflecting from the real problem which was dereliction of duty by the “architects” who took a laissez-faire stance on state management instead of providing structure. Worked on a couple of those. Never again.

Practically the whole point of encapsulation is gated access to data, putting constraints on sharing, compressing the possible state space of the system closer to the desired state space.