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From: mkant@glinda.oz.cs.cmu.edu (Mark Kantrowitz)
Newsgroups: comp.lang.lisp
Subject: Re: Destructive Operations
Message-ID: <12814@pt.cs.cmu.edu>
Date: 26 Apr 91 19:07:48 GMT
References: <1351@ai.cs.utexas.edu> <1991Apr25.052624.14541@Think.COM> <595@lysator.liu.se>
Organization: Carnegie-Mellon University, CS/RI
Lines: 13

In article <595@lysator.liu.se> bellman@lysator.liu.se (Thomas Bellman) writes:
>Well, I don't know very much about CommonLisp, but in good ol'
>InterLISP, there was a function called DREMOVE, which did *not*
>require the user to store the result back, *even* if it had to remove
>the first element.  It is easy to remove the first element of a list.

If I remember correctly (it's been six or seven years since I used an
1108), the InterLisp-D functions DREMOVE and DISPLACE had problems if
the arguments shared list structure. This could lead to rather hideous
bugs. Imagine trying to debug code and running into a circular list in
the debugger.

--mark