> We can think about applying something like that for cancellation — without going for full immutability, we can let cancelled analysis to work with the old hal

> We can think about applying something like that for cancellation — without going for full immutability, we can let cancelled analysis to work with the old half-state, while we switch to the new one if we want to cancel analysis basin on old state why do we need garbage collection and two states? And how is garage collection way different from full immutability? In my understanding this is the same thing but with extra steps, you have to copy element instead updating it in place because existing copy might be used by already running analysis. Reference counting should give you similar benefits with less work needed, usually everything have only single reference (no analysis is using anything) and we could optimize it to modify it in place in that case, otherwise you just need to copy it once without requiring garbage collection later. Am I missing something?