I didn't, actually! I don't know how else I'd express it, but I'm thinking of Rust, Haskell, etc's "step beyond" plain static typing with sum/ADTs, pattern matc

I didn't, actually! I don't know how else I'd express it, but I'm thinking of Rust, Haskell, etc's "step beyond" plain static typing with sum/ADTs, pattern matching, and exlusion of null. A seemingly small detail, but it does feel like it makes the type system more deterministic and "stronger", in a sense.