Simple queue

core.clj

(defn new-queue []
  (atom clojure.lang.PersistentQueue/EMPTY))

(defn put [queue value]
  (when (nil? value)
    (throw (ex-info "nil is not allowed" {:value value})))
  (swap! queue conj value)
  (vec (seq @queue)))

(defn take [queue]
  (let [value (peek @queue)]
    (swap! queue pop)
    value))


(def q (new-queue))

(put q 1)
(put q 2)
(put q 3)
(put q 4)
(put q nil)

(take q)