This is great stuff! As a Haskell fan who uses Elixir (and Erlang) in my day job, I'm really looking forward to seeing how we can leverage more of the new set-theoretic type features showing up in Elixir. Revisions seem like something I've never really seen before in any of the type systems I've used, so I'm excited to see how it can be leveraged in a real production system. Thanks for the post.