1 (defun fold-right (op init seq) 2 (if (null seq) 3 init 4 (funcall op 5 (car seq) 6 (fold-right op init (cdr seq))))) 7 (defun fold-left (op init seq) 8 (labels ( 9 (iter (result rest) 10 (if (null rest) 11 result 12 (iter (funcall op result (car rest)) 13 (cdr rest))))) 14 (iter init seq)))