corectl

 1(define (state->number state)
 2  (if (number? state)
 3    state
 4    (cond
 5      ((eq? state 'on)      pkt-on)
 6      ((eq? state 'off)     pkt-off)
 7      ((eq? state 'restore) pkt-restore)
 8      (else (error "unknown LED state")))))
 9
10(define (assoc->list asc)
11  (fold (lambda (x ys)
12          (let ((pair (assoc x asc)))
13            (append ys
14                    (list (if pair
15                            (state->number (cdr pair))
16                            pkt-restore)))))
17        '() (range num-leds)))
18
19(define (marshal asc)
20  (define padding (make-list pkt-pad 0))
21
22  (list->u8vector
23    (append
24      (list pkt-hdr pkt-rw)
25      (assoc->list asc)
26      padding)))