channels.clj

(require '[clojure.core.async :as async])

(def file ["a" "b" {:url "http://ip.jsontest.com/"} "d" "e" {:url "http://time.jsontest.com"}])
(println "Loaded file..." (pr-str file))

(defmacro while-let
      "Repeatedly executes body while test expression is true, evaluating the body with binding-form bound to the value of test."
          [[form test] & body]
              `(loop [~form ~test]
                          (when ~form
                                         ~@body
                                                      (recur ~test))))

(let [output (async/chan)
      v (println "Creating channels")
      channels (map (fn [line]
                      (let [rendered-line (async/chan 1)]
                        (async/go
                            (if (map? line)
                              (do
                                ;; Would go do an HTTP request here
                                (async/<! (async/timeout 1000))
                                (async/>! rendered-line (str "HTTP:" (:url line)))
                                (async/close! rendered-line))
                              (do
                                (async/>! rendered-line line)
                                (async/close! rendered-line))))
                        rendered-line)
                      ) file)
     ]
    (let [result (atom "")]

      (async/go
        (doseq [channel channels]
          (swap! result str "\n" (async/<! channel))
          ))
      (println @result))
  )