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bug#15301: 24.3; description of function booleanp

From: Glenn Morris
Subject: bug#15301: 24.3; description of function booleanp
Date: Sat, 07 Sep 2013 13:33:48 -0400
User-agent: Gnus (www.gnus.org), GNU Emacs (www.gnu.org/software/emacs/)

唐成龙 wrote:

> Chapter 1.3.2
> Page 3
> The description of booleanp in reference: Return non-nil if object is
> one of the two canonical boolean values: t or nil.
> But in my practice, these two non-canonical values including () and '()
> also cause booleanp returning t. Is it a question?

Those are just different ways of writing nil. It says so in the very
same chapter that you cite.

    As far as the Lisp reader is concerned, `()' and `nil' are
    identical: they stand for the same object, the symbol `nil'. The
    different ways of writing the symbol are intended entirely for human
    readers. After the Lisp reader has read either `()' or `nil', there
    is no way to determine which representation was actually written by
    the programmer.

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