;; insert : number list -> list
;; inserts n into l, assuming it is sorted

(define (insert n l)
  (cond
    [(empty? l) (cons n empty)]
    [(cons? l)
     (cond
       [(<= n (first l)) (cons n l)]
       [else (cons (first l) (insert n (rest l)))])]))

;; examples:

(insert 2 empty) 'shouldbe (cons 2 empty)
(insert 2 (cons 3 empty)) 'shouldbe (cons 2 (cons 3 empty))
(insert 2 (cons 1 empty)) 'shouldbe (cons 1 (cons 2 empty))


;; sort : list -> list
;; to sort l, in ascending order
(define (sort l)
  (cond
    [(empty? l) empty]
    [(cons? l)  (insert (first l)
                   (sort (rest l)))]))

;; examples
(sort empty) 'shouldbe empty
(sort (cons 1 (cons 2 empty)))
'shouldbe
(cons 1 (cons 2 empty))

(sort (cons 2 (cons 1 empty)))
'shouldbe
(cons 1 (cons 2 empty))