[DonaldPShimoda]

Most complex, perhaps, but not "most advanced". I don't think there's necessarily a meaningful "correct" choice for that title, but surely one of the proof assistant languages would be a more likely candidate?

(I don't say this to be disparaging of TypeScript's type system, by any means — it's very interesting stuff!)

[dimitropoulos]

good points, let's get negated types and higher kinded types in there then you've got yourself a deal. maybe regex thrown in too for flavor