Without comments to test Adrian

core.clj

(ns async.core
  (:require [clojure.core.async :as async :refer :all]
            [clojure.data.generators :as gen])
  (:gen-class))

(defrecord SyncMessage [text wake])

(defmacro forever [& body]
  `(while true
     ~@body))

(defn boring
  [talk]
  (let [wake (chan)
        noise #(str % ": " (gen/string "*" (inc (rand-int 15))))]
    (go
     (doseq [n (iterate inc 1)]
       (>! talk (->SyncMessage (noise n) wake))
       (<! (timeout (int (* 500 (rand)))))
       (<! wake)))
    talk))

(defn multiplex
  [& ins]
  (let [out (chan)]
    (go
     (forever
      (let [[result _] (alts! ins)]
        (>! out result))))
    out))

(defn -main
  [& args]
  (let [src (multiplex (boring (chan))
                       (boring (chan)))]
    (dotimes [n 5]
      (let [msg1 (<!! src)
            msg2 (<!! src)]
        (println (:text msg1))
        (println (:text msg2))
        (>!! (:wake msg1) true)
        (>!! (:wake msg2) true)))
    (println "\nYou're both boring, I'm leaving.")))

Try to determine:

• Whether or not a function has side-effects
• What the value of each function is
• What the output of the program is
• Any other "interesting" events in the life of the program

Fixed performance bug in this version