I don't think it is too clever. I think it solves the problem idiomatically. I.e., it uses reduce, which is exactly correct. Programmers should be encouraged to understand what is correct, why it is correct, and then propagate. For a trivial operation like average, true, one doesn't need to be "clever". But by understanding what "reduce" is for a trivial case, one can then start applying it to much more complex problems. upvote.