I was referring to the type system in the formal "specification" sense, not the implementation details of the compiler, such as the compiler's runtime (Go, or, in the past, JavaScript/Node). it's too bad there's no specification for TypeScript the way there is for JavaScript and many other things (most?). in that sense, the performance of the type system is uncoupled from the semantics of the type system itself (as the Go port has thoroughly illustrated!).

I mentioned Hindley-Milner because I am under the belief that the HM system (as in OCaml) is, in the same formal/semantic/specification sense, perhaps more advanced. but, as is often with these things, the rubber meets the road on which one of them has been shown to actually run Doom, lol, to which TypeScript is currently the undisputed king.