I don't get it. In the case of the vector-add function, once you've happened to notice the more general solution, implementing it will take a couple of minutes

I don't get it. In the case of the vector-add function, once you've happened to notice the more general solution, implementing it will take a couple of minutes. It's not comparable to an optimization, which would normally increase the risk of code errors -- it is a simplification, which would decrease the risk of code errors. Two minutes to make a minor simplification and learn a generally good way of approaching things with the tool at hand (clojure)? Count me in.