I would be interested how much their approach scales in terms of code size, since they use likely SMT solvers to guarantee having no arithmetic overflows (which is more than Rust guarantees). Ideally as comparison with compile times of Rust programs.
It used to take a couple of seconds to compile Wuffs' standard library. It's back down to a few hundred milliseconds.
https://nigeltao.github.io/blog/2020/dumbindent.html#compila...
At least based on a quick skim of the docs, they use a combination of programmer assertions, interval arithmetic, and their type system for bounds checking and ensuring no arithmetic overflows.
Also loop invariants etc must all be annotated. I would be more interested how they plan to handle IO effects or if they want to omit that.
I'm sorry but I don't understand this statement. Can you re-phrase it?
> I would be more interested how they plan to handle IO effects or if they want to omit that.
I'm not sure exactly what you're asking for, but see the Coroutines, Effects and I/O pages in https://github.com/google/wuffs/tree/main/doc/note