robots making sounds

soundbots.rkt

#lang racket

(require rsound)

(define *midi-notes* (range 38 85))

(define (choice lst)
  (list-ref lst (random (length lst))))

(define (sublist lst midpoint width)
  (let ([begin-index (if (> midpoint width)
                         (- midpoint width)
                         0)]
        [end-index (if (<= midpoint (- (length lst) width))
                       (+ midpoint width)
                       (length lst))])
    (for/list ([i (in-range begin-index end-index)])
      (list-ref lst i))))

(define (limited-choice lst prev-elem)
  (let* ([prev-index (index-of lst prev-elem)]
         [new-lst (sublist lst prev-index 4)])
    (choice new-lst)))

(define (play-note note)
  (play (synth-note "vgame"
                    17
                    note
                    (/ (default-sample-rate) 4))))

(define-syntax-rule (make-sound-bot bot-name peer)
  (define bot-name
    (thread
     (λ ()
       (let loop ()
         (let ([msg (thread-receive)])
           (match msg
             [number? (let ([chosen-note (limited-choice *midi-notes* msg)])
                        (play-note chosen-note)
                        (sleep 0.33)
                        (thread-send peer chosen-note)
                        (loop))]
             ['quit null])))))))

(make-sound-bot bot-1 bot-2)
(make-sound-bot bot-2 bot-1)

(thread-send bot-1 (choice *midi-notes*))
(sleep 90)
(kill-thread bot-1)