1 665c255d 2023-08-04 jrmu (defun fold-right (op init seq)
 2 665c255d 2023-08-04 jrmu   (if (null seq)
 3 665c255d 2023-08-04 jrmu       init
 4 665c255d 2023-08-04 jrmu       (funcall op
 5 665c255d 2023-08-04 jrmu 	       (car seq)
 6 665c255d 2023-08-04 jrmu 	       (fold-right op init (cdr seq)))))
 7 665c255d 2023-08-04 jrmu (defun fold-left (op init seq)
 8 665c255d 2023-08-04 jrmu   (labels (
 9 665c255d 2023-08-04 jrmu 	   (iter (result rest)
10 665c255d 2023-08-04 jrmu 	     (if (null rest)
11 665c255d 2023-08-04 jrmu 		 result
12 665c255d 2023-08-04 jrmu 		 (iter (funcall op result (car rest))
13 665c255d 2023-08-04 jrmu 		       (cdr rest)))))
14 665c255d 2023-08-04 jrmu     (iter init seq)))
15 665c255d 2023-08-04 jrmu (fold-right #'* 1 '(1 2 3 4 5))
16 665c255d 2023-08-04 jrmu (fold-left #'* 1 '(1 2 3 4 5))