This doesnt seems to be meaningfully different from Rust.
> does not require tracing garbage collection
Just call it garbage collection.
(Applies in two ways: if you think that garbage collection subsumes reference counting then this language doesn’t require garbage collection in the sense that it also doesn’t require reference counting; if you think that garbage collection does not subsume reference counting then there’s no point in saying three words when you can say two.)
It's less specified than rust. For example, you can bind references to individual collection elements here. It doesn't seem to prohibit borrowing a dynamically indexed element either, which is one hell of a static analysis lift. Seems like you can also have simultaneous references to distinct static indices (e.g. &mut arr[0] and &mut arr[1]) as long as you don't do invalidating operations, which isn't expressible in NLL or polonius. That's feasible for a borrowchecker at least.
It's great to have it all spec'd out. However, I think specs like this suffer the same fate as war plans: they get modified quickly as soon as implementation begins. Nonetheless, it's good to have a clear idea of where you're headed. I just wouldn't call it "Final."
Yes, but remember is the last appendix to a book, and book provides the context for this appendix. So yes, in that sense, it's just another one attempting to address the memory-safety issues of C. At least this one uses C like syntax and doesn't require C programmers to learn some alien syntax. Of course, this is just a spec, Rust is well and truly live in the environment. The book is more interesting than the spec.
> does not require tracing garbage collection
Just call it garbage collection.
(Applies in two ways: if you think that garbage collection subsumes reference counting then this language doesn’t require garbage collection in the sense that it also doesn’t require reference counting; if you think that garbage collection does not subsume reference counting then there’s no point in saying three words when you can say two.)
[0] https://c3-lang.org
some just delegate more or less to the implementation
i read trying to assess if it's more or less expressible than rust's current nll or the future polonius and honestly there's nothing there