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diff --git a/devdocs/elisp/mapping-functions.html b/devdocs/elisp/mapping-functions.html deleted file mode 100644 index 2f920180..00000000 --- a/devdocs/elisp/mapping-functions.html +++ /dev/null @@ -1,62 +0,0 @@ - <h3 class="section">Mapping Functions</h3> <p>A <em>mapping function</em> applies a given function (<em>not</em> a special form or macro) to each element of a list or other collection. Emacs Lisp has several such functions; this section describes <code>mapcar</code>, <code>mapc</code>, <code>mapconcat</code>, and <code>mapcan</code>, which map over a list. See <a href="creating-symbols#Definition-of-mapatoms">Definition of mapatoms</a>, for the function <code>mapatoms</code> which maps over the symbols in an obarray. See <a href="hash-access#Definition-of-maphash">Definition of maphash</a>, for the function <code>maphash</code> which maps over key/value associations in a hash table. </p> <p>These mapping functions do not allow char-tables because a char-table is a sparse array whose nominal range of indices is very large. To map over a char-table in a way that deals properly with its sparse nature, use the function <code>map-char-table</code> (see <a href="char_002dtables">Char-Tables</a>). </p> <dl> <dt id="mapcar">Function: <strong>mapcar</strong> <em>function sequence</em> -</dt> <dd> -<p><code>mapcar</code> applies <var>function</var> to each element of <var>sequence</var> in turn, and returns a list of the results. </p> <p>The argument <var>sequence</var> can be any kind of sequence except a char-table; that is, a list, a vector, a bool-vector, or a string. The result is always a list. The length of the result is the same as the length of <var>sequence</var>. For example: </p> <div class="example"> <pre class="example">(mapcar #'car '((a b) (c d) (e f))) - ⇒ (a c e) -(mapcar #'1+ [1 2 3]) - ⇒ (2 3 4) -(mapcar #'string "abc") - ⇒ ("a" "b" "c") -</pre> - -<pre class="example">;; <span class="roman">Call each function in <code>my-hooks</code>.</span> -(mapcar 'funcall my-hooks) -</pre> - -<pre class="example">(defun mapcar* (function &rest args) - "Apply FUNCTION to successive cars of all ARGS. -Return the list of results." - ;; <span class="roman">If no list is exhausted,</span> - (if (not (memq nil args)) - ;; <span class="roman">apply function to CARs.</span> - (cons (apply function (mapcar #'car args)) - (apply #'mapcar* function - ;; <span class="roman">Recurse for rest of elements.</span> - (mapcar #'cdr args))))) -</pre> - -<pre class="example">(mapcar* #'cons '(a b c) '(1 2 3 4)) - ⇒ ((a . 1) (b . 2) (c . 3)) -</pre> -</div> </dd> -</dl> <dl> <dt id="mapcan">Function: <strong>mapcan</strong> <em>function sequence</em> -</dt> <dd> -<p>This function applies <var>function</var> to each element of <var>sequence</var>, like <code>mapcar</code>, but instead of collecting the results into a list, it returns a single list with all the elements of the results (which must be lists), by altering the results (using <code>nconc</code>; see <a href="rearrangement">Rearrangement</a>). Like with <code>mapcar</code>, <var>sequence</var> can be of any type except a char-table. </p> <div class="example"> <pre class="example">;; <span class="roman">Contrast this:</span> -(mapcar #'list '(a b c d)) - ⇒ ((a) (b) (c) (d)) -;; <span class="roman">with this:</span> -(mapcan #'list '(a b c d)) - ⇒ (a b c d) -</pre> -</div> </dd> -</dl> <dl> <dt id="mapc">Function: <strong>mapc</strong> <em>function sequence</em> -</dt> <dd><p><code>mapc</code> is like <code>mapcar</code> except that <var>function</var> is used for side-effects only—the values it returns are ignored, not collected into a list. <code>mapc</code> always returns <var>sequence</var>. </p></dd> -</dl> <dl> <dt id="mapconcat">Function: <strong>mapconcat</strong> <em>function sequence separator</em> -</dt> <dd> -<p><code>mapconcat</code> applies <var>function</var> to each element of <var>sequence</var>; the results, which must be sequences of characters (strings, vectors, or lists), are concatenated into a single string return value. Between each pair of result sequences, <code>mapconcat</code> inserts the characters from <var>separator</var>, which also must be a string, or a vector or list of characters. See <a href="sequences-arrays-vectors">Sequences Arrays Vectors</a>. </p> <p>The argument <var>function</var> must be a function that can take one argument and returns a sequence of characters: a string, a vector, or a list. The argument <var>sequence</var> can be any kind of sequence except a char-table; that is, a list, a vector, a bool-vector, or a string. </p> <div class="example"> <pre class="example">(mapconcat #'symbol-name - '(The cat in the hat) - " ") - ⇒ "The cat in the hat" -</pre> - -<pre class="example">(mapconcat (lambda (x) (format "%c" (1+ x))) - "HAL-8000" - "") - ⇒ "IBM.9111" -</pre> -</div> </dd> -</dl><div class="_attribution"> - <p class="_attribution-p"> - Copyright © 1990-1996, 1998-2022 Free Software Foundation, Inc. <br>Licensed under the GNU GPL license.<br> - <a href="https://www.gnu.org/software/emacs/manual/html_node/elisp/Mapping-Functions.html" class="_attribution-link">https://www.gnu.org/software/emacs/manual/html_node/elisp/Mapping-Functions.html</a> - </p> -</div> |