Difference Lists in Clojure

dlist.clj

(defn dl 
  [& elements] 
  (fn [x] (concat elements x)))

(defn dl-un 
  [l] 
  (l nil))
(defn dl-concat 
  [& lists] 
  (fn [x] ((apply comp lists) x)))

(def example (dl-un (dl-concat (dl 1) (dl 2 3) (dl) (dl 4))))