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Improve flatten-tree documentation

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* doc/lispref/lists.texi (Building Lists):
* lisp/subr.el (flatten-tree):
Don’t imply that flatten-tree modifies its argument.
Clarify wording.
This commit is contained in:
Paul Eggert 2018-12-17 09:55:06 -08:00
parent 8664ba18c7
commit a5995a326d
2 changed files with 10 additions and 14 deletions
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10
doc/lispref/lists.texi
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@ -668,10 +668,10 @@ their elements).
@end defun
@defun flatten-tree tree
Take @var{tree} and "flatten" it.
This always returns a list containing all the terminal nodes, or
leaves, of @var{tree}. Dotted pairs are flattened as well, and nil
elements are removed.
This function returns a ``flattened'' copy of @var{tree}, that is,
a list containing all the non-@code{nil} terminal nodes, or leaves, of
the tree of cons cells rooted at @var{tree}. Leaves in the returned
list are in the same order as in @var{tree}.
@end defun
@example
@ -680,7 +680,7 @@ elements are removed.
@end example
@defun number-sequence from &optional to separation
This returns a list of numbers starting with @var{from} and
This function returns a list of numbers starting with @var{from} and
incrementing by @var{separation}, and ending at or just before
@var{to}. @var{separation} can be positive or negative and defaults
to 1. If @var{to} is @code{nil} or numerically equal to @var{from},

14
lisp/subr.el
View file

@ -5449,17 +5449,13 @@ This function is called from lisp/Makefile and leim/Makefile."
file)
(defun flatten-tree (tree)
"Take TREE and \"flatten\" it.
This always returns a list containing all the terminal nodes, or
\"leaves\", of TREE. Dotted pairs are flattened as well, and nil
elements are removed.
"Return a \"flattened\" copy of TREE.
In other words, return a list of the non-nil terminal nodes, or
leaves, of the tree of cons cells rooted at TREE. Leaves in the
returned list are in the same order as in TREE.
\(flatten-tree \\='(1 (2 . 3) nil (4 5 (6)) 7))
=> (1 2 3 4 5 6 7)
TREE can be anything that can be made into a list. For each
element in TREE, if it is a cons cell return its car
recursively. Otherwise return the element."
=> (1 2 3 4 5 6 7)"
(let (elems)
(while (consp tree)
(let ((elem (pop tree)))