From: Wayne A. Christopher
Subject: Re: Are "destructive" functions really destructive?
Date: Sat, 02 Dec 1989 00:55:15 +0000
Message-ID: <20197@pasteur.Berkeley.EDU>

I think there are other reasons to use destructive operations besides
efficiency.  If you have a large and complex data structure, sometimes
you have to walk down a long path of pointers to get to the item you want,
and it's a lot easier to change it in place than to write a long string
of setf's to make sure everything points to the right place.  In a case
like that, if you can guarantee that you will never change the first item
of a list, you really want delete, et al to work "the right way".

	Wayne