我是SICP新手,正在编写一个向量元素长度函数,该函数将向量作为参数并返回长度向量
以下是迄今为止我所做的尝试,但没有给出结果
#lang racket (define colors (vector "red" "orange" "yellow" "green" "blue" "indigo" "violet")) (define (length-of-vector-elements vct) (vector-map vector-length vct)) (length-of-vector-elements colors)
所需输出为: (length-of-vector-elements colors) => #(3 6 6 5 4 6 6)
(length-of-vector-elements colors) => #(3 6 6 5 4 6 6)
要素 colors 是字符串,不是向量,所以必须使用 string-length :
colors
string-length
#lang racket (define colors (vector "red" "orange" "yellow" "green" "blue" "indigo" "violet")) (define (length-of-vector-elements vct) (vector-map string-length vct)) (length-of-vector-elements colors)
=> #(3 6 6 5 4 6 6)
#(3 6 6 5 4 6 6)