;; I'm not sure e.g.
;; (mapf (cycle f1 f2 f3) collection)
;; is a big improvement over
;; (map #(%1 %2) (cycle f1 f2 f3) collection)
;;
;; In theory, this would have to be further generalized to any number of
;; collections (a la map).
(defn mapf [fs coll]
  (lazy-seq
   (when-let [fns (seq fs)
              s (seq coll)]
     (cons ((first fns) (first s)) (mapf (rest fns) (rest s))))))