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From: hoey@zogwarg.etl.army.mil (Dan Hoey)
Newsgroups: comp.lang.lisp
Subject: Re: How does one quote an atom in Sun CL (correction)
Summary: Quotes, constants, and silliness
Message-ID: <657@zogwarg.etl.army.mil>
Date: 8 May 91 15:44:21 GMT
References: <1991May6.205017.15237@cs.mcgill.ca> <1991May7.181305.1973@jpl-devvax.jpl.nasa.gov>
Organization: Naval Research Laboratory, Washington, DC
Lines: 27

In article <1991May7.181305.1973@jpl-devvax.jpl.nasa.gov> charest@ai-cyclops.jpl.nasa.gov writes:
>The following works as a general purpose quoting function for any LISP datum:

>(defun kwote (thing)
>  (if (constantp thing)
>    thing
>    `(quote ,thing)))

No.  The CONSTANTP test is incorrect for constants that do not
evaluate to themselves.  For instance (KWOTE 'PI) -> PI fails the
expected (EQL 'PI (EVAL (KWOTE 'PI))).

The traditional way of defining KWOTE is

    (defun kwote (thing) `',thing)

although the alternate definition

    (defun kwote (thing)
      (if (and (constantp thing) (eql thing (eval thing)))
	thing
	`',thing))

is functionally acceptable and arguably preferable.

If you're about to lose your connection, you can try (DEFUN KWOTE
(-\))`',-\))