Thank you, that clarifies the idea for me and it's an interesting approach. It seems like an "all in" design that you might apply to e.g. an interpreter. Of co

Thank you, that clarifies the idea for me and it's an interesting approach. It seems like an "all in" design that you might apply to e.g. an interpreter. Of course in practice we don't abandon Rust's slice iterators to achieve basic observers or backreferences, and I've definitely tripped over "someone else is already borrowing this thing" runtime errors.