timestate

racket/syndicate/drivers/timestate.rkt

@@ -0,0 +1,21 @@
+#lang syndicate/actor
+
+(provide (struct-out later-than)
+         stop-when-timeout)
+
+(require/activate syndicate/drivers/timer)
+
+(struct later-than (msecs) #:prefab)
+
+(actor #:name 'drivers/timestate
+       (during (observe (later-than $msecs))
+         (define timer-id (gensym 'timestate))
+         (field [expired? #f])
+         (on-start (send! (set-timer timer-id msecs 'absolute)))
+         (on (message (timer-expired timer-id _)) (expired? #t))
+         (assert #:when (expired?) (later-than msecs))))
+
+(define-syntax-rule (stop-when-timeout relative-msecs body ...)
+  (let ((timer-id (gensym 'timeout)))
+    (on-start (send! (set-timer timer-id relative-msecs 'relative)))
+    (stop-when (message (timer-expired timer-id _)) body ...)))

racket/syndicate/examples/actor/timestate.rkt

@@ -0,0 +1,15 @@
+#lang syndicate/actor
+
+(require/activate syndicate/drivers/timestate)
+
+(actor #:name 'demo-timeout
+       (on-start (printf "Starting demo-timeout\n"))
+       (on-stop (printf "Stopping demo-timeout\n"))
+       (stop-when-timeout 3000 (printf "Three second timeout fired\n")))
+
+(actor #:name 'demo-later-than
+       (on-start (printf "Starting demo-later-than\n"))
+       (on-stop (printf "Stopping demo-later-than\n"))
+       (field [deadline (+ (current-inexact-milliseconds) 5000)])
+       (stop-when (asserted (later-than (deadline)))
+                  (printf "Deadline expired\n")))