Newsgroups: comp.lang.lisp
From: hoey@zogwarg.etl.army.mil (Dan Hoey)
Date: 8 May 91 15:44:21 GMT
Subject: Re: How does one quote an atom in Sun CL (correction)

char...@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
(-\))`',-\))