use future in weird way

encasulate-future.rkt

#lang racket/base
(require racket/future
         racket/async-channel
         racket/function
         racket/match)

(define process-map (make-hasheq))
(struct pid ())
(struct process (id fu ch))

(define (process-send p msg)
  (define np (hash-ref process-map (process-id p)
                       p))
  (async-channel-put (process-ch np) msg)
  (hash-set! process-map (process-id p) (touch (process-fu np))))

(define (^friend my-name
                 [id (pid)]
                 [ch (make-async-channel)])
  (process id
           (future
            (thunk (match (async-channel-get ch)
                     [(list 'ping from)
                      (printf "ping from ~a~n" my-name)
                      (process-send from 'pong)
                      (^friend my-name id ch)]
                     ['pong
                      (printf "pong from ~a~n" my-name)
                      (^friend my-name id ch)])))
           ch))

(define bob (^friend "Bob"))
(define jack (^friend "Jack"))

(process-send bob (list 'ping jack))
(process-send bob (list 'ping jack))
(process-send bob (list 'ping jack))