But that is my point: if host language doesn't have feature X, you still can implement that feature yourself, can't you? If host language is untyped, then writ

But that is my point: if host language doesn't have feature X, you still can implement that feature yourself, can't you? If host language is untyped, then write your own type system. Another example: Java has no co-routines, has no continuations, but Kotlin (written in Java) does. They compile Kotlin code with co-routines into finite state machines in Java.