(defn wget []
  (slurp "http://xx.yy"))

(defn show [s]
  (print s)
  (flush))

(defn snag-futures [n]
  ;; Lazy q will be evaluated in chunks of 32 launching that many
  ;; futures at a time:
  (let [q (for [_ (range n)]
            (do
              (show "+")
              (future (let [x (wget)]
                        (show ".")
                        x))))]
    ;; mapv reterns a vec, not a lazy seq. Hm, launching all futures
    ;; by (vec q) does not seem to help performance:
    (mapv deref q)))

(defn snag-quotes [n]
  (let [c (chan)]
    ;; Posting to the channel here, each from a separate "thread". An
    ;; exception that prevents a put would deadlock the reader down
    ;; there:
    (dotimes [n n]
      (go (>! c (try
                  (show "+")
                  (let [x (wget)]
                    (show ".")
                    x)
                  (catch Exception e
                    ;; (str (.getMessage e))
                    e)))))
    ;; Reading n items from the channel here. The vec is delivered
    ;; through a go-block result channel. There is also go-loop for
    ;; this:
    (<!! (go (loop [n n
                    acc []]
               (if (zero? n)
                 acc
                 (recur (dec n)
                        (conj acc (<! c)))))))))