(defn get-items
  ([] (get-items 0))
  ([page] (let [{:keys [items more?]} (receive-items page)]
            (concat items (when more?
                            (lazy-seq (get-items (inc page))))))))

_
  (iter-objects [this bucket]
    (iter-objects this bucket nil))

  (iter-objects [this bucket prev-result]
    (lazy-seq
     (let [result (if prev-result
                    (s3/list-next-batch-of-objects creds prev-result)
                    (s3/list-objects creds bucket))
           {:keys [object-summaries
                   truncated?]} result]
       (concat object-summaries
               (when truncated?
                 (lazy-seq (iter-objects this bucket result)))))))

_
  (iter-objects [this bucket]
    (iter-objects this bucket nil))

  (iter-objects [this bucket prev-result]
    (lazy-seq
     (let [result (if prev-result
                    (s3/list-next-batch-of-objects creds prev-result)
                    (s3/list-objects creds bucket))
           {:keys [truncated?
                   object-summaries]} result]
       (concat object-summaries
               (when truncated?
                 (iter-objects this bucket result))))))

(defn get-items
  []
  {:items [1 2 3]
   :has-more (rand-nth [true true false])})


(defn get-items*
  [prev-result]
  (-> (get-items)
      (assoc :continue? (not (false? (:has-more prev-result))))))


(->> (iterate get-items* nil)
     (drop 1)
     (take-while :continue?)
     (mapcat :items))