[bccdee]

> Rust by default doesn't really encourage the group-element mindset and people have to work against the language in order to do it.

It's true that you don't see stuff like arena allocators very often, but Rust's lifetime/ownership semantics mean it's often best for related pieces of data to be owned by a single parent, which unifies their lifetimes such that they all start and stop being valid at the same time. I suppose that's only part of the equation, since an arena has you allocate everything at once in a continuous block, which has performance advantages.

Still, I can't help but see an underlying conceptual symmetry there. I feel like the scoped arena school of memory management would be nicely complemented by compiler lifetime analysis. Arenas definitely simplify lifetime issues, but that feels like an opportunity to experiment with additional static compiler checks, not a reason to eschew them. I'd love to see a language which required explicit deallocation but enforced it with linear types.