* bug#15301: 24.3; description of function booleanp
@ 2013-09-07 3:14 唐成龙
2013-09-07 17:33 ` Glenn Morris
0 siblings, 1 reply; 2+ messages in thread
From: 唐成龙 @ 2013-09-07 3:14 UTC (permalink / raw)
To: 15301
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?
^ permalink raw reply [flat|nested] 2+ messages in thread
* bug#15301: 24.3; description of function booleanp
2013-09-07 3:14 bug#15301: 24.3; description of function booleanp 唐成龙
@ 2013-09-07 17:33 ` Glenn Morris
0 siblings, 0 replies; 2+ messages in thread
From: Glenn Morris @ 2013-09-07 17:33 UTC (permalink / raw)
To: 唐成龙; +Cc: 15301
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.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2013-09-07 3:14 bug#15301: 24.3; description of function booleanp 唐成龙
2013-09-07 17:33 ` Glenn Morris
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