Buffered vector as a value - not stored in an atom

buffer.cljs

(ns DarrenN.stateless.buffer)
;; create-buffer returns a vector scoped to size. When new items are added
;; they are passed to functions in add-listeners. If the vector is at its
;; size limit then items are shifted off the front of the vector and 
;; passed to the functions in destroy-listeners

;; Callbacks for adding/removing item from vector
(def destroy-listeners [(fn [i] (print (str i " removed")))])
(def add-listeners [(fn [i] (print (str i " added")))])

(defn add-item [i v]
  "Add an item to the vector and call listeners on added item"
  (doseq [f add-listeners] (f i))
  (conj v i))

(defn remove-item [v]
  "Remove item from vector triggering listeners on removed item"
  (doseq [f destroy-listeners] (f (first v)))
  (vec (rest v)))

(defn create-buffer [size v]
  "Return a function that keeps a vector at size when adding"
  (fn [item v]
    (let [newv (add-item item v)]
      (if (> (count v) size)
        (remove-item newv)
        newv))))

;; Loop from 0 to 99 filling a 10 slot queue
(let [ct 0
      queue (create-buffer 10 [])
      vt []]
  (loop [v vt
         c ct]
    (when (> 100 c)
      (recur (queue c v) (inc c)))))