Minimal Dining Philosophers (http://en.wikipedia.org/wiki/Dining_philosophers_problem)

dining-philosophers.clj

(def place-settings 5)
(def chopsticks (repeatedly place-settings #(ref true)))
(def philosophers (map #(agent %) (partition 2 1 chopsticks chopsticks)))

(defn sleep [] (Thread/sleep (rand-int 1000)))
(def eat sleep)
(def think sleep)

(defn toggle-chopsticks [cs pred?]
  (dosync
    (when (pred? cs)
      (doseq [c cs] (alter c not))
      true)))
(defn get-chopsticks [cs] (toggle-chopsticks cs #(every? ensure %)))
(defn release-chopsticks [cs] (toggle-chopsticks cs (constantly true)))

(defn dine [cs]
  (when (get-chopsticks cs)
    (eat)
    (release-chopsticks cs))
  (think)
  (send-off *agent* dine)
  cs)

(doseq [p philosophers]
  (send-off p dine))