[kaba0]

I think some variant of it is a must in low-level languages like Rust, even if as vague as “this given arena owns this and will free these objects”.

For a higher level hobby language I’m designing, I’m thinking of doing a similar concept, but with runtime overhead - basically every object would be “synchronized” in Java’s parlance, but to make it efficient most lockings would be elided at compile time via move semantics. So data races couldn’t happen (also, could possibly do a better job at escape analysis).

The primary reason I’m thinking about that is that we really shouldn’t be using non-thread safe primitives anymore — Clojure did get this right. That should be left as a compiler optimization if it can prove that that given code runs inside a “alone”.