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Re: Elisp: What does ''nil mean?


From: Thomas Gehrlein
Subject: Re: Elisp: What does ''nil mean?
Date: 16 May 2003 18:16:15 +0200
User-agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.1

David Kastrup <address@hidden> writes:

> Thomas Gehrlein <address@hidden> writes:
> 
> > David Kastrup <address@hidden> writes:
> > 
> > > Thomas Gehrlein <address@hidden> writes:
> > > 
> > > > The following line is from easy-menu-create-menu:
> > > > 
> > > > ((eq keyword :active) (setq enable (or arg ''nil)))
> > > > 
> > > > It is part of a (cond ...).
> > > > 
> > > > What does "''nil" mean?
> > > 
> > > The same as '(quote nil), an unevaluated list with the two members
> > > quote and nil.
> > 
> > Is this the same as (quote (quote nil))?
> 
> It is, like (quote nil), the result of evaluating (quote (quote nil)).
> 
> > Why would you quote nil and not evaluate it?
> 
> To make it different from nil, while evaluating to it eventually.

Thank you.  I think now I understand.


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