It's fine since all the detailed goop is at the implementation level. Programmers need not care. Making a distinction between known and unknown calls in the im

It's fine since all the detailed goop is at the implementation level. Programmers need not care. Making a distinction between known and unknown calls in the implementation is not only a good thing, but in a language with first-class functions it is all but inevitable because the performance win is so large. (The majority of calls are known, and known calls can be compiled significantly more efficiently than any general purpose call machinery.)