1 12687dd9 2023-08-04 jrmu ;; The first three lines of this file were inserted by DrScheme. They record metadata
 2 12687dd9 2023-08-04 jrmu ;; about the language level of this file in a form that our tools can easily process.
 3 12687dd9 2023-08-04 jrmu #reader(lib "htdp-intermediate-reader.ss" "lang")((modname 19.1.4) (read-case-sensitive #t) (teachpacks ((lib "draw.ss" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ((lib "draw.ss" "teachpack" "htdp")))))
 4 12687dd9 2023-08-04 jrmu (define (squared>? x c)
 5 12687dd9 2023-08-04 jrmu   (> (* x x) c))
 6 12687dd9 2023-08-04 jrmu 
 7 12687dd9 2023-08-04 jrmu ;filter : predicate list-of-numbers
 8 12687dd9 2023-08-04 jrmu ;Filters out all numbers in a-lon where the predicate of the number evaluates to false.  Retains all numbers that evaluate to true.
 9 12687dd9 2023-08-04 jrmu (define (filter1 predicate a-lon t)
10 12687dd9 2023-08-04 jrmu   (cond
11 12687dd9 2023-08-04 jrmu     [(empty? a-lon) empty]
12 12687dd9 2023-08-04 jrmu     [(predicate (first a-lon) t) (cons (first a-lon)
13 12687dd9 2023-08-04 jrmu                                        (filter1 predicate (rest a-lon) t))]
14 12687dd9 2023-08-04 jrmu     [else (filter1 predicate (rest a-lon) t)]))
15 12687dd9 2023-08-04 jrmu 
16 12687dd9 2023-08-04 jrmu #|
17 12687dd9 2023-08-04 jrmu (filter1 squared>? (list 4 5) 10)
18 12687dd9 2023-08-04 jrmu = (cons 4 (filter1 squared>? (list 5) 10))
19 12687dd9 2023-08-04 jrmu 
20 12687dd9 2023-08-04 jrmu (cond
21 12687dd9 2023-08-04 jrmu   [(empty? (list 4 5)) empty]
22 12687dd9 2023-08-04 jrmu   [(squared>? (first (list 4 5)) 10) (cons (first (list 4 5))
23 12687dd9 2023-08-04 jrmu                                           (filter1 squared>? (rest (list 4 5)) 10))]
24 12687dd9 2023-08-04 jrmu   [else (filter squared>? (rest (list 4 5)))])
25 12687dd9 2023-08-04 jrmu 
26 12687dd9 2023-08-04 jrmu (cond
27 12687dd9 2023-08-04 jrmu   [false empty]
28 12687dd9 2023-08-04 jrmu   [true (cons 4
29 12687dd9 2023-08-04 jrmu               (filter1 squared>? (list 5) 10))]
30 12687dd9 2023-08-04 jrmu   [else (filter squared>? (rest (list 4 5)))])
31 12687dd9 2023-08-04 jrmu 
32 12687dd9 2023-08-04 jrmu (cons 4 (filter1 squared>? (list 5) 10))
33 12687dd9 2023-08-04 jrmu |#
34 12687dd9 2023-08-04 jrmu 
35 12687dd9 2023-08-04 jrmu ;below : list-of-numbers number -> list-of-numbers
36 12687dd9 2023-08-04 jrmu ;Given a-lon, return all numbers below a-number as a list-of-numbers.
37 12687dd9 2023-08-04 jrmu 
38 12687dd9 2023-08-04 jrmu (define (below a-lon a-number)
39 12687dd9 2023-08-04 jrmu   (filter1 < a-lon a-number))
40 12687dd9 2023-08-04 jrmu 
41 12687dd9 2023-08-04 jrmu ;above: list-of-numbers number -> list-of-numbers
42 12687dd9 2023-08-04 jrmu ;Given a-lon, return all numbers above a-number as a list-of-numbers.
43 12687dd9 2023-08-04 jrmu 
44 12687dd9 2023-08-04 jrmu (define (above a-lon a-number)
45 12687dd9 2023-08-04 jrmu   (filter1 > a-lon a-number))