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; Improve documentation of 'append'

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* doc/lispref/lists.texi (Building Lists):
* src/fns.c (Fappend): Improve documentation of 'append'.  (Bug#73427)
This commit is contained in:
Eli Zaretskii 2024-09-23 14:41:34 +03:00
parent c1f2501f55
commit c8ed48b990
2 changed files with 30 additions and 1 deletions
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24
doc/lispref/lists.texi
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@ -666,6 +666,17 @@ This once was the usual way to copy a list, before the function
(append [a b] "cd" nil) (append [a b] "cd" nil)
@result{} (a b 99 100) @result{} (a b 99 100)
@end group @end group
@end example
@cindex list of characters of a string
@cindex convert string to list of its characters
Here's how to convert a string into a list of its characters:
@example
@group
(append "abcd" nil)
@result{} (97 98 99 100)
@end group
@end example @end example
With the help of @code{apply} (@pxref{Calling Functions}), we can append With the help of @code{apply} (@pxref{Calling Functions}), we can append
@ -690,10 +701,12 @@ all the lists in a list of lists:
Here are some examples where the final argument is not a list: Here are some examples where the final argument is not a list:
@example @example
@group
(append '(x y) 'z) (append '(x y) 'z)
@result{} (x y . z) @result{} (x y . z)
(append '(x y) [z]) (append '(x y) [z])
@result{} (x y . [z]) @result{} (x y . [z])
@end group
@end example @end example
@noindent @noindent
@ -702,6 +715,17 @@ not a list, the sequence's elements do not become elements of the
resulting list. Instead, the sequence becomes the final @sc{cdr}, like resulting list. Instead, the sequence becomes the final @sc{cdr}, like
any other non-list final argument. any other non-list final argument.
As an exception, if all the arguments but the last are @code{nil} and
the last argument is not a list, the return value is that last argument
unchanged:
@example
@group
(append nil nil "abcd")
@result{} "abcd"
@end group
@end example
@defun copy-tree tree &optional vectors-and-records @defun copy-tree tree &optional vectors-and-records
This function returns a copy of the tree @var{tree}. If @var{tree} is a This function returns a copy of the tree @var{tree}. If @var{tree} is a
cons cell, this makes a new cons cell with the same @sc{car} and cons cell, this makes a new cons cell with the same @sc{car} and

7
src/fns.c
View file

@ -719,7 +719,12 @@ The result is a list whose elements are the elements of all the arguments.
Each argument may be a list, vector or string. Each argument may be a list, vector or string.
All arguments except the last argument are copied. The last argument All arguments except the last argument are copied. The last argument
is just used as the tail of the new list. is just used as the tail of the new list. If the last argument is not
a list, this results in a dotted list.
As an exception, if all the arguments except the last are nil, and the
last argument is not a list, the return value is that last argument
unaltered.
usage: (append &rest SEQUENCES) */) usage: (append &rest SEQUENCES) */)
(ptrdiff_t nargs, Lisp_Object *args) (ptrdiff_t nargs, Lisp_Object *args)