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value< manual entry adjustments (bug#69709)

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* doc/lispref/sequences.texi (Sequence Functions):
Explain lexicographical ordering.  Note the dual nature of `nil`.
Mention the depth limit.
This commit is contained in:
Mattias Engdegård 2024-03-29 15:25:22 +01:00
parent d2d5e51439
commit f04bd55687
1 changed files with 21 additions and 3 deletions
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24
doc/lispref/sequences.texi
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@ -461,7 +461,7 @@ This function returns non-@code{nil} if @var{a} comes before @var{b} in
the standard sorting order; this means that it returns @code{nil} when
@var{b} comes before @var{a}, or if they are equal or unordered.
the arguments @var{a} and @var{b} must have the same type.
The arguments @var{a} and @var{b} must have the same type.
Specifically:
@itemize @bullet
@ -471,7 +471,11 @@ Numbers are compared using @code{<} (@pxref{definition of <}).
Strings are compared using @code{string<} (@pxref{definition of
string<}) and symbols are compared by comparing their names as strings.
@item
Conses, lists, vectors and records are compared lexicographically.
Conses, lists, vectors and records are compared lexicographically. This
means that the two sequences are compared element-wise from left to
right until they differ, and the result is then that of @code{value<} on
the first pair of differing elements. If one sequence runs out of
elements before the other, the shorter sequence comes before the longer.
@item
Markers are compared first by buffer, then by position.
@item
@ -489,8 +493,22 @@ Examples:
(value< "dog" "cat") @result{} nil
(value< 'yip 'yip) @result{} nil
(value< '(3 2) '(3 2 0)) @result{} t
(value< [3 2 1] [3 2 0]) @result{} nil
(value< [3 2 "a"] [3 2 "b"]) @result{} t
@end example
@noindent
Note that @code{nil} is treated as either a symbol or an empty list,
depending on what it is compared against:
@example
(value< nil '(0)) @result{} t
(value< 'nib nil) @result{} t
@end example
@noindent
There is no limit to the length of sequences (lists, vectors and so on)
that can be compared, but @code{value<} may fail with an error if used
to compare circular or deeply nested data structures.
@end defun
@cindex sequence functions in seq