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#lang racket
(define (scale-tree tree factor)
(cond ((null? tree) nil)
((not (pair? tree)) (* tree factor))
(else (cons (scale-tree (car tree) factor)
(scale-tree (cdr tree) factor)))))
(define (scale-tree tree factor)
(map (lambda (sub-tree)
(if (pair? sub-tree)
(scale-tree subtree factor)
(* sub-tree factor)))
tree))
;; analogous to, but we now also have to test when to recurse in the middle of the tree
;; (define (square-list items)
;; (if (null? items)
;; (list)
;; (cons (square (car items)) (square-list (cdr items)))))
(define (square-tree tree)
(cond ((null? tree) nil)
((not (pair? tree)) (* tree tree))
(else (cons (square-tree (car tree))
(square-tree (cdr tree))))))
(define test-tree (list 1 (list 2 (list 3 4) 5) (list 6 7)))
((lambda ()
(display (square-tree test-tree))))
;; Can I also pass some state combining sequence and recursive operations?
(define (square-tree-map tree)
(map (lambda (subtree)
(if (pair? subtree)
(square-tree-map subtree)
(* subtree subtree)))
tree))
((lambda ()
(display (square-tree-map test-tree))))
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