gistfile1.txt

(defmachine PaymentsMachine
  (state :user-submitted
         (on-in (fn [data]
                  (log/put "User submitted ...")
                  (send-email "..."))))
  (state :sent-off
         (on-in (fn [data]
                  (log/put "sent payment"))))
  (state :error
         (on-in (fn [data]
                  (log/put "...")))
         (after 3 :days (fn [])))
  (state :notified-user-of-error)
  (state :complete)

  (on :init (fn [data]
              (if (valid? data)
                (transition :user-submitted {:data ...}))))

  (accepts :complete))