其他提示
如果你不担心除去多余的括号,然后以下口齿不清码会的工作:
(defun rpn-to-inf (pre)
(if (atom pre)
pre
(cond ((eq (car (last pre)) 'setf)
(list (rpn-to-inf (first pre)) '= (rpn-to-inf (second pre))))
((eq (car (last pre)) 'expt)
(list (rpn-to-inf (first pre)) '^ (rpn-to-inf (second pre))))
(t (list (rpn-to-inf (first pre))
(car (last pre))
(rpn-to-inf (second pre)))))))
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