Created
April 9, 2012 20:45
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(define (make-object name) (list 'name name)) | |
(define object->name cadr) | |
(define names (list "john" "paul" "george" "ringo")) | |
(define objects (map make-object names)) | |
(define (contains? objects names) | |
(define (names-contains? name) | |
(let loop ((names names)) | |
(cond | |
((null? names) #f) | |
((string=? name (car names)) #t) | |
(else (loop (cdr names)))))) | |
(let loop ((object-names (map object->name objects))) | |
(cond | |
((null? object-names) | |
#t) | |
((not (names-contains? (car object-names))) | |
#f) | |
(else (loop (cdr object-names)))))) | |
(define (p message result) | |
(display message) | |
(display result) | |
(newline)) | |
(p "This test passed: " (contains? objects names)) | |
(p "This test passed: " (not (contains? (cons (make-object "duncan") objects) names))) | |
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