update list.scm

A method to Sort a list of numbers in Scheme... It also has other operations in Scheme

(define ls (list 1 2 3 4 5))
(define temp1 (list))
(define (update lis pos val)
  (let ((n 0) (temp1 (list)) )
    (let loop ((temp lis) (lsk 0))
    (if (= pos (+ n 1)) (begin
                        (set! temp1 (append temp1 (list val)))
                        (set! n (+ 1 n))
                        (set! temp (cdr temp))
                         (loop temp 0))
;;                          (display temp1)
        (begin
          (if (null? temp) (display temp1) (begin
          (set! temp1 (append temp1 (list(car temp))))
          (set! temp (cdr temp))
          (set! n (+ n 1))
          (loop temp 0)))))
   )))