(use srfi-1)

(define (sort list)
  (cond ((= (length list) 1) list)
        (else (let* ((mid (/ (length list) 2))
                     (left (sort (take list mid)))
                     (right (sort (drop list mid))))
                (merge left right)))))

(define (merge left right)
  (cond ((or (null? left) (null? right))
         (append left right))
        ((< (car left) (car right))
         (cons (car left) (merge (cdr left) right)))
        (else
         (cons (car right) (merge left (cdr right))))))

(sort '(8 4 3 7 6 5 2 1))