That's cool; I think another way of doing it is to allow programs to request a sandbox where the GC doesn't go so they can do all of the pointer-arithmeticking

That's cool; I think another way of doing it is to allow programs to request a sandbox where the GC doesn't go so they can do all of the pointer-arithmeticking they want as long as all their pointers fall within the sandbox by the time they're written through or dereferenced.