;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-intermediate-lambda-reader.ss" "lang")((modname 28.6.1) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ())))
; Worked exercise 28.2.2

; any-satisfies? : (X -> boolean) list-of-X -> boolean
(check-expect (any-satisfies? even? (list 3 5 9)) false)
(check-expect (any-satisfies? even? (list 3 5 8)) true)
(define (over-5? x) (> x 5))
(check-expect (any-satisfies? over-5? (list 2 3 4)) false)
(check-expect (any-satisfies? over-5? (list 2 6 4)) true)
;(check-expect (any-satisfies? prime? (list 2 6 4)) true)
;(check-expect (any-satisfies? prime? (list 8 6 4)) false)
; commented these out because I haven't defined prime? yet

(define (any-satisfies? test? things)
  (cond [(empty? things) false]
        [(cons? things)
         (or (test? (first things))
             (any-satisfies? test? (rest things)))]))


; any-compares? : (number number -> boolean) number list-of-numbers -> boolean
(check-expect (any-compares? >= 5 (list 2 5 1)) true)
(check-expect (any-compares? > 5 (list 2 5 1)) false)
(check-expect (any-compares? = 5 (list 2 5 1)) true)
(check-expect (any-compares? = 5 (list 2 6 1)) false)
(check-expect (any-compares? < 5 (list 2 6 1)) true)
(check-expect (any-compares? < 5 (list 7 6 8)) false)

(define (any-compares? compare? num nums)
  ; compare?       number number -> boolean
  ; num            number
  ; nums           list of numbers
  (any-satisfies? (lambda (num-from-list) (compare? num-from-list num))
                  nums))