28 lines
1.1 KiB
Racket
28 lines
1.1 KiB
Racket
|
#lang prospect-monolithic
|
||
|
;; Demonstrates a (hopefully soon historical!) bug in Syndicate.
|
||
|
;;
|
||
|
;; When the bug exists, this program receives four SCN events in
|
||
|
;; total, whereas it should receive only two.
|
||
|
;;
|
||
|
;; While metamessages are "echo cancelled", and receivers only ever
|
||
|
;; get one copy of a sent metamessage no matter how many metas there
|
||
|
;; are, state changes are not (yet). Issuing a quick enough "pulse" of
|
||
|
;; metaassertion while maintaining interest in it leads to an "echo":
|
||
|
;; multiple receipts of the pulse.
|
||
|
;;
|
||
|
;; The fix is to adjust the implementation of state change
|
||
|
;; notifications to cancel the echo for metaassertions.
|
||
|
|
||
|
(require prospect/pretty)
|
||
|
|
||
|
(spawn-network
|
||
|
(spawn (lambda (e counter)
|
||
|
(and e
|
||
|
(let ((new-counter (+ counter 1)))
|
||
|
(printf "Received event ~a:\n~a\n" new-counter (prospect-pretty-print->string e))
|
||
|
(transition (+ counter 1) '()))))
|
||
|
0
|
||
|
(list (scn/union (assertion (at-meta 'x))
|
||
|
(subscription 'x #:meta-level 1))
|
||
|
(scn (subscription 'x #:meta-level 1)))))
|