> I don't think this approach is necessarily incompatible with garbage collection; theoretically a language like Go could have separate vector and slice types l

> I don't think this approach is necessarily incompatible with garbage collection; theoretically a language like Go could have separate vector and slice types like Rust does, and I think that would make these types of optimizations much easier! Absolutely. It's not a GC issue, it's a design issue. Adding this kind of control would make the language harder to use. Making the hard case easier to handle for experts makes the easy case harder to handle for everyone.