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Thanks, that makes a lot of sense (basically Mobx but fine-grained). When I mentioned diffing, I meant for updating state objects like lists. Your `<For/>` element only updates if a new list is created, but only re-renders the changed elements. I assume this is accomplished by diffing the old and the new list?

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Yes you are correct. Use diffing here actually very similar to VDOM libraries. It was more performant(and consistent) than just propagating the change purely through manipulation of a proxy. Especially if you consider things like batching.

Thanks. Batching was more efficient with diffing because you can avoid keeping track of which array indices changed within the same batch?

Yes and keeping the order of application. I actually played with this for a bit. Early Solid let you basically codify mutations you could send in as data. I thought it was interesting to do something like Redux where instead of producing the next state you produced the mutations that would be applied, and then applied them at a granular level instead of diffing. But when you add time into the picture you actually have keep track of more. I'm not saying it's impossible to tackle this just the people I know who have been working at this always hit limitations where they need to fall back to diffing anyway. I think it would take some doing to determine where the book keeping cost would be worth it. It is rarely as simple as more granular is better.

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