Subject: Re: intersection
From: Erik Naggum <>
Date: 28 Jan 2004 15:02:26 +0000
Newsgroups: comp.lang.lisp
Message-ID: <>

* Tuang
| The Hyperspec says the following about intersection:

      If one of the lists contains duplicate elements, there may be
      duplication in the result.

  Sets implemented as lists are defined on the presence of members of
  the set in the list.  It is strictly speaking an error to duplicate
  members of the set in the list representation, but this error is hard
  to detect inexpensively, so the rational course of action is to allow
  it with suitable hand-waving.  The above is an instance of precisely
  such hand-waving.

Erik Naggum | Oslo, Norway                                      2004-028

Act from reason, and failure makes you rethink and study harder.
Act from faith, and failure makes you blame someone and push harder.