(define (list-ref-default l n default)
  (if (>= n (length l)) default (list-ref l n)))

(define-for-syntax list-ref-default list-ref-default) ; doesn't work, but it would be nice if it did

(define-for-syntax list-ref-default (lambda (l n default)
                                      (if (>= n (length l)) default (list-ref l n))))