I feel like you picked at the least interesting aspects of my comment. It continues to be frustrating to talk to you. :-( And yes, you can index by byte offset

I feel like you picked at the least interesting aspects of my comment. It continues to be frustrating to talk to you. :-( And yes, you can index by byte offset in a zero cost way by converting the string to a byte slice first. Have you used Rust strings (or any similarly designed string abstraction) in anger before? It might help to get some boots-on-the-ground experience with it.