Vale's “generational references” sound like some kind of holy grail, which makes me worry I'm missing something. Surely someone has tried them before? Why aren't they already in common use? I think they would constrain memory allocation and promote heap fragmentation, which might be fine on a system with ample 64-bit address space, but could be troublesome for WebAssembly for example. They also don't seem like they avoid the concurrency issues that Rust's borrowing model can.

Also, it's unfortunate that Vale is one letter away from Vala.