Returning Proxies from Index/IndexMut

[kornel]

Custom DSTs could also help, where the extra data would be hidden in the fat pointer:

Custom DST Discussion

We recently postponed the custom DST RFC. But I wanted to continue the conversation both about its design and potential applications. If you’d like to catch up, read my most recent summary comment. Anyone, when we left it, @AtheMathmo and I were discussing trying to mock up how their library would look if implemented with this feature. I’m eager to hear the results. =)