SICP 問題 2.31
(define (tree-map fn tree) (map (lambda (sub-tree) (if (pair? sub-tree) (tree-map fn sub-tree) (fn sub-tree))) tree)) (define (sqaure x) (* x x)) (define (square-tree tree) (tree-map square tree))
(define (tree-map fn tree) (map (lambda (sub-tree) (if (pair? sub-tree) (tree-map fn sub-tree) (fn sub-tree))) tree)) (define (sqaure x) (* x x)) (define (square-tree tree) (tree-map square tree))