message-struct and assertion-struct

racket/syndicate/core.rkt

@@ -11,6 +11,9 @@
 
          (struct-out process)
 
+         assertion-struct
+         message-struct
+
          (struct-out seal)
          sealof
 
@@ -116,6 +119,12 @@
 ;; A PID is a Nat.
 ;; A Label is a PID or 'meta.
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Thin veneers over `struct` for declaring intent.
+
+(define-syntax-rule (assertion-struct item ...) (struct item ... #:prefab))
+(define-syntax-rule (message-struct item ...) (struct item ... #:prefab))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Seals are used by protocols to prevent the routing tries from
 ;; examining internal structure of values.

racket/syndicate/examples/actor/box-and-client.rkt

@@ -1,8 +1,8 @@
 #lang syndicate
 ;; Simple mutable box and count-to-infinity box client.
 
-(struct set-box (new-value) #:transparent)
-(struct box-state (value) #:transparent)
+(message-struct set-box (new-value))
+(assertion-struct box-state (value))
 
 (spawn (field [current-value 0])
        (assert (box-state (current-value)))