DRY (by using wait-until-time)

os-userland-example.rkt

@@ -17,7 +17,7 @@
        (wait (message-handlers
 	      [`(request ,reply-addr ,pattern)
 	       (spawn (lambda ()
-			(define answer (begin body ...))
+			(define answer (let () body ...))
 			(send `(reply ,reply-addr ,answer))))
 	       (loop)])))]))
 
@@ -50,11 +50,9 @@
 (define (sleep-driver)
   (rpc-service `(sleep ,msecs)
 	       (send `(display (Sleeping ,msecs)))
-	       (wait (message-handlers)
-		     (meta-message-handlers
-		      [((time-evt (+ (current-time) msecs)) => now)
-		       (send `(display "\n"))
-		       now]))))
+	       (define now (wait-until-time (+ (current-time) msecs)))
+	       (send `(display "\n"))
+	       now))
 
 (define (main)
   (spawn display-driver)