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From: gat@forsight.jpl.nasa.gov (Erann Gat)
Newsgroups: comp.lang.lisp
Subject: Re: EQUAL on circular lists
Message-ID: <1991Jun8.002630.22596@elroy.jpl.nasa.gov>
Date: 8 Jun 91 00:26:30 GMT
References: <2849@prles2.prl.philips.nl>
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In article <2849@prles2.prl.philips.nl> kostelij@apolloway.prl.philips.nl (T. Kostelijk 43897) writes:
>Does anyone have an extended version of EQUAL which can determine in 
>finite time whether two trees of conses have the same printed
>(possibly infinite) representation?

Try:

(defun printed-representations-equal-p (l1 l2)
  (let ( (*print-circle* t) )
    (string= (format nil "~S" l1) (format nil "~S" l2))))