race in atom

atom.clj

(ns cljstm.core)

(defn start-thread [f]
  (.start  (Thread.  f)))

(defmacro thread [& body]
  `(start-thread
     (fn [] ~@body)))

(defn sleep [x]
  (Thread/sleep x))

(def my-state (atom nil))

(defn swap-the-atom []
  (thread
    (swap! my-state
           (fn [s]
             (sleep 150)
             (println "Attempt with " s)
             "ups")))
  (thread
    (dotimes [x 42]
      (swap! my-state (constantly x))
      (sleep 50)))

  (thread
    (while (not (= (deref my-state) "ups"))
      (println  @my-state)
      (sleep 30))
    (println "OK: " @my-state)))

(swap-the-atom)