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 20.2.3) (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 filter1 : (X Y -> boolean) (listof X) Y -> (listof X)
 5 12687dd9 2023-08-04 jrmu 
 6 12687dd9 2023-08-04 jrmu (define (filter1 rel-op alon t)
 7 12687dd9 2023-08-04 jrmu   (cond
 8 12687dd9 2023-08-04 jrmu     [(empty? alon) empty]
 9 12687dd9 2023-08-04 jrmu     [(rel-op (first alon) t) 
10 12687dd9 2023-08-04 jrmu      (cons (first alon)
11 12687dd9 2023-08-04 jrmu        (filter1 rel-op (rest alon) t))]
12 12687dd9 2023-08-04 jrmu     [else
13 12687dd9 2023-08-04 jrmu       (filter1 rel-op (rest alon) t)]))