Re: Predicate for true lists

["Basil L. Contovounesios" <contovob@tcd.ie>]

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Eli Zaretskii <eliz@gnu.org> writes:

>> From: "Basil L. Contovounesios" <contovob@tcd.ie>
>> Cc: Paul Eggert <eggert@cs.ucla.edu>,  <emacs-devel@gnu.org>
>> Date: Sat, 07 Jul 2018 18:04:28 +0300
>> 
>>  This function returns the number of elements in @var{sequence}.  If
>> -@var{sequence} is a dotted list, a @code{wrong-type-argument} error is
>> -signaled; if it is a circular list, a @code{circular-list} error is
>> -signaled.  For a char-table, the value returned is always one more
>> -than the maximum Emacs character code.
>> +@var{sequence} does not satisfy @code{sequencep} or is a dotted list,
>
> It is better to say "If the argument is not a sequence, or is a dotted
> list, ...".
>
>> +a @code{wrong-type-argument} error is signaled; if it is a circular
>
> Please try to avoid passive tense, it usually makes the text longer
> and less clear.  I'd suggest
>
>   The function signals the @code{wrong-type-argument} error if the
>   argument is not a sequence or is a dotted list; it signals the
>   @code{circular-list} error if the argument is a circular list.

Thanks, I agree.  How's the updated patch:


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From 41fda89f5a161521dcc303e79f308b7c13a61b9d Mon Sep 17 00:00:00 2001
From: "Basil L. Contovounesios" <contovob@tcd.ie>
Date: Sat, 7 Jul 2018 19:33:08 +0300
Subject: [PATCH] Fix (length NON-SEQUENCE) documentation

Suggested by Eli Zaretskii <eliz@gnu.org> in the following threads:
https://lists.gnu.org/archive/html/emacs-devel/2018-07/msg00171.html
https://lists.gnu.org/archive/html/emacs-devel/2018-07/msg00206.html

* doc/lispref/sequences.texi (Sequence Functions): Mention that
'length' signals a 'wrong-type-argument' also when given a
non-sequencep argument.
---
 doc/lispref/sequences.texi | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/doc/lispref/sequences.texi b/doc/lispref/sequences.texi
index 59faf2b4f1..188a345114 100644
--- a/doc/lispref/sequences.texi
+++ b/doc/lispref/sequences.texi
@@ -71,13 +71,15 @@ Sequence Functions
 @cindex list length
 @cindex vector length
 @cindex sequence length
+@cindex bool-vector length
 @cindex char-table length
 @anchor{Definition of length}
-This function returns the number of elements in @var{sequence}.  If
-@var{sequence} is a dotted list, a @code{wrong-type-argument} error is
-signaled; if it is a circular list, a @code{circular-list} error is
-signaled.  For a char-table, the value returned is always one more
-than the maximum Emacs character code.
+This function returns the number of elements in @var{sequence}.  The
+function signals the @code{wrong-type-argument} error if the argument
+is not a sequence or is a dotted list; it signals the
+@code{circular-list} error if the argument is a circular list.  For a
+char-table, the value returned is always one more than the maximum
+Emacs character code.
 
 @xref{Definition of safe-length}, for the related function @code{safe-length}.
 
-- 
2.18.0


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Basil