http.async.client callback counting body parts

countbodyparts.clj

;; counting body parts
(http-r/execute-request
 c (http-r/prepare-request :get "http://localhost:8080/json")
 :part (fn [resp part]
         (let [counter (if (realized? (:body resp)) (:body resp) (atom 0))]
           (swap! counter inc)
           (println :p part)
           [counter :continue]))
 :completed (fn [resp]
              (println :d @@(:body resp);atom within a promise
                       )))