DrRacket合并结构列表

Question

我想知道如何将列表合并为一个大列表。例如 让我们说我们得到一个结构， (define-struct fruits (type number)) 基本上给出了这个

(list 
     (list (make-fruits 'Apple 4) (make-fruits 'Orange 3) (make-fruits 'Pears 5))
     (list (make-fruits 'Peach 4))
     (list (make-fruits 'Kiwi 5) (make-fruits 'Banana 2)))

如何将所有这些列表结构合并为一个大列表？使用local，map，foldr，filter和不使用递归的任何方式。

Answer 1

#lang racket
(define-struct fruits (type number) #:transparent)

(apply append
       (list 
        (list (make-fruits 'Apple 4) (make-fruits 'Orange 3) (make-fruits 'Pears 5))
        (list (make-fruits 'Peach 4))
        (list (make-fruits 'Kiwi 5) (make-fruits 'Banana 2))))

结果：

(list (fruits 'Apple 4) (fruits 'Orange 3) (fruits 'Pears 5) (fruits 'Peach 4) (fruits 'Kiwi 5) (fruits 'Banana 2))