#lang syndicate/actor
;; Hello-worldish "bank account" example.

(struct account (balance) #:prefab)
(struct deposit (amount) #:prefab)

(actor (react (field [balance 0])
              (assert (account (balance)))
              (on (message (deposit $amount))
                  (balance (+ (balance) amount)))))

(actor (react (on (asserted (account $balance))
                  (printf "Balance changed to ~a\n" balance))))

(actor (until (asserted (observe (deposit _))))
       (send! (deposit +100))
       (send! (deposit -30)))