Сортировка списка

(define e-real "2.7")

(define (decode l)
  (define (iter i e l)
    (if (null? l)
        (list (list i e))
        (if (equal? (car l) e)
            (iter (+ i 1) (car l) (cdr l))
            (cons (list i e) (iter 1 (car l) (cdr l))))))
(iter 1 (car l) (cdr l)))

(define (delenie a b t)
  (let ((k (quotient (* a (expt 10 t)) b)))
    (string-append (number->string (quotient k (expt 10 t)))
                   "."
                   (number->string (remainder k (expt 10 t))))))

(define (e)
  (define (iter i S f)
    (if (= i 1000)
        S
        (iter (+ i 1) (+ S (/ 1 (* f i))) (* f i))))
  (let ((k (iter 2 2 1)))
     (delenie (numerator k) (denominator k) 60)))
(define e-real "2.71828")