Oh! Can Not Diary

おきゃんなダイアリー

reverse

テスト。

(define A "abcde")
(define B "1234")

(define rev-list
  (lambda (list new-list)
    (cond
     ((null? list) new-list)
     (else (rev-list (cdr list) (cons (car list) new-list))))))

(define rev
  (lambda (str)
    (cond
     ((null? str) null)
     (else (list->string (rev-list (string->list str) '()))))))

(rev (string-append (rev A) (rev B))) ;1234abcde