There's a spectrum here. Someone even more explicit than you may insist that `average` should be split up into explicit bindings for the mapping to Int, the sum

There's a spectrum here. Someone even more explicit than you may insist that `average` should be split up into explicit bindings for the mapping to Int, the sum, and the count. Also, for non-toy examples, there are real benefits to composing transformations, so that you don't pay the memory and performance costs of assigning intermediate sequences.