I'm planning on doing something similar to what I did for pattern matching [1]: basically building something entirely standalone that fits in 2k LOC or so, and explains the basics (i.e. nominal typing plus basic sub-typing), hopefully such that people can then take that and extend it.

As for _when_ I'll do that, that depends on when I can convince my inner critic to actually commit to the idea :)

[1]: https://github.com/yorickpeterse/pattern-matching-in-rust