Proposed: memorysafe reference types

[alsonkemp]

I'm back to learning Rust. Focused on making sure that I understand memory safety before starting to code (as opposed to my usual back-into-it by starting with coding and then learning as necessary). I'm fairly happy with my understanding of memory safety but I'm not clear about the various reference types and their compositions[1]. A session covering this topic along with relevant code examples would be lovely. Additional links would also be lovely.

Note: I'm in SF so would love it if this issue were labelled appropriately (which I can't do?).

---

1. https://manishearth.github.io/blog/2015/05/27/wrapper-types-in-rust-choosing-your-guarantees/; https://users.rust-lang.org/t/confused-between-box-rc-cell-arc/10946;