;; SRFI 1: リスト ライブラリ http://www.chino-js.com/tech/srfi/srfi-1/srfi-1.html#zip (use srfi-1) (unfold-right null? car cdr (fold cons '() '(1 2 3 4 5))) ;; (1 2 3 4 5) (let ((seq (cut <> cons '() '(1 2 3 4 5))) (rev (cut <> null? car cdr <>))) (values (rev unfold-right (seq fold)) (rev unfold (seq fold-right)))) ;; (1 2 3 4 5) ;; (1 2 3 4 5) (let ((seq (cut <> cons '() '(1 2 3 4 5))) (rev (cut <> null? car cdr <>))) (equal? (rev unfold-right (seq fold)) (rev unfold (seq fold-right)))) ;; #t