syndicate-2017/racket/prospect-monolithic/examples/chat-no-quit-world-no-nesti...

48 lines
2.2 KiB
Racket

#lang prospect-monolithic
(require racket/set)
(require (only-in racket/string string-trim))
(require "../drivers/tcp.rkt")
(require "../demand-matcher.rkt")
(define (spawn-session them us)
(define user (gensym 'user))
(define remote-detector (advertise (?! (tcp-channel ? ? ?))))
(define peer-detector (advertise `(,(?!) says ,?)))
(define (send-to-remote fmt . vs)
(message (tcp-channel us them (string->bytes/utf-8 (apply format fmt vs)))))
(define (say who fmt . vs)
(unless (equal? who user) (send-to-remote "~a ~a\n" who (apply format fmt vs))))
(list (send-to-remote "Welcome, ~a.\n" user)
(spawn
(lambda (e peers)
(match e
[(message (tcp-channel _ _ bs))
(transition peers (message `(,user says ,(string-trim (bytes->string/utf-8 bs)))))]
[(message `(,who says ,what))
(transition peers (say who "says: ~a" what))]
[(scn assertions)
(if (trie-empty? (trie-project assertions remote-detector))
(quit (send-to-remote "Goodbye!\n"))
(let ((new-peers (trie-project/set/single assertions peer-detector)))
(define arrived (set-subtract new-peers peers))
(define departed (set-subtract peers new-peers))
(transition new-peers
(list (for/list [(who arrived)] (say who "arrived."))
(for/list [(who departed)] (say who "departed."))))))]
[#f #f]))
(set)
(scn/union
(subscription `(,? says ,?)) ;; read actual chat messages
(subscription (advertise `(,? says ,?))) ;; observe peer presence
(advertisement `(,user says ,?)) ;; advertise our presence
(subscription (tcp-channel them us ?)) ;; read from remote client
(subscription (advertise (tcp-channel them us ?))) ;; monitor remote client
(advertisement (tcp-channel us them ?)) ;; we will write to remote client
))))
(spawn-tcp-driver)
(spawn-demand-matcher (advertise (tcp-channel (?!) (?! (tcp-listener 5999)) ?))
(observe (tcp-channel (?!) (?! (tcp-listener 5999)) ?))
spawn-session)