Gradual typing isn't exactly a TypeScript invention: Typed Racket is gradually typed, has unions and intersections (which in turn date from further back than TR), refinement types, occurrence types, and even comes with a guarantee that typed code won't violate contracts. If the Racket runtime detects a contract violation, blame will always be assigned to untyped code. TR does more than TS does, and it was designed and implemented earlier.

> It sounded a bit condescending to me.

I didn't read k_bx's comment as belittlement of TypeScript: anything that makes JavaScript better is obviously a good thing! (Since we can't get rid of it.) But, as a matter of fact, TypeScript isn't pushing “what types can do”.