gistfile1.clj

(defn agent-die [state]
  (println (str (:id state) ": Alas!  I am slain!"))
  (remove-watch *agent* :stepper)
  (swap! remaining-agents dec)
  (assoc state :alive false))

(defn agent-fn [state]
  (let [new-x (mod ((rand-dir) (:x state)) len-x)
        new-y (mod ((rand-dir) (:y state)) len-y)
        next-cell (at-loc new-x new-y)]
    (if-let [foe (deref next-cell)]
      (do
        (send foe agent-die)
        (println "There can only be one!")
        (println (str (:id state) " killed " (:id @foe)
                      " at " new-x ", " new-y))))
    (if (:alive state)
      (do
        (reset! next-cell *agent*)
        (println (str (:id state) " moving to " new-x " " new-y))
        (assoc state :x new-x :y new-y))
      (remove-watch *agent* :stepper))))

(defn create-agent [id x y]
  (let [new-agent (agent {:id id :x x :y y :alive true})]
    (add-watch new-agent :stepper
               (fn [_ agt _ _]
                 (Thread/sleep (rand-int 3000))
                 (send agt agent-fn)))
    new-agent))