gistfile1.scm

(let ([server (make-server-socket "4649")])
  (display "Echo server: START\n")
  (let loop ([conn (socket-accept server)])
    (let ([pid (spawn
                (lambda ()
                  (display "child start\n")
                  (receive
                    [('connection conn)
                     (let loop ([data (socket-recv conn 100)])
                       (cond
                        [(zero? (bytevector-length data))
                         (socket-close conn)
                         (display "Echo server: STOP\n")]
                        [else
                         (format #t "received ~s\n" (utf8->string data))
                         (socket-send conn data 0)
                         (loop (socket-recv conn 100))]))]))
                '((rnrs) (mosh concurrent) (mosh) (mosh socket)))])
    (! pid `(connection ,conn)))
  (loop (socket-accept server)))
  (socket-close server))