#lang/bsl+

; LON is one of:
; – empty
; – (cons Number LON)
; interpretation: a list of numbers

; LON -> LON
; created a sorted version of one-lon

(check-expect (sort '(13 0 1 2 3 4 5 6 7 8 9 10 11 12 14 15))
                    '(0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15))

(define (sort one-lon)
   (cond
     [(empty? one-lon) '()]
     [(cons? one-lon)
      (ryan (first one-lon) (sort (rest one-lon)))]))

; Number LON -> LON
; puts n into one-lon according to ascending order
; WHAT DO WE KNOW: one-lon is sorted in ascending order
; because ryan is called inside of sort with (sort (rest ...))

(check-expect (ryan 13 (list 11 12 14 15)) (list 11 12 13 14 15))
(check-expect (ryan 13 empty) (list 13))

(define (ryan n one-lon)
   (cond
     [(empty? one-lon) (list n)]
     [(cons? one-lon)
      (if (<= (first one-lon) n)
          (cons (first one-lon) (ryan n (rest one-lon)))
          (cons n one-lon))]))

(ryan 13 empty)
(check-expect (ryan 13 empty) (list 12))

prog:1:0: read: expected a single space after `#lang'