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<h4 class="subsection">14.15.3 <code>@expansion{}</code> (==&gt;): Indicating an Expansion</h4>

<p><a name="index-Expansion_002c-indicating-878"></a><a name="index-Macro-expansion_002c-indicating-879"></a><a name="index-expansion-880"></a>
When an expression is a macro call, it expands into a new expression. 
You can indicate the result of the expansion with the
<code>@expansion{}</code> command.

  <p>The <code>@expansion{}</code> command is displayed as &lsquo;<samp><span class="samp">==&gt;</span></samp>&rsquo;
in Info and HTML, and as a long arrow with a flat base in the printed
output.

  <p>For example, the following

<pre class="example">     @lisp
     (third '(a b c))
         @expansion{} (car (cdr (cdr '(a b c))))
         @result{} c
     @end lisp
</pre>
  <p class="noindent">produces

<pre class="lisp">     (third '(a b c))
         ==&gt; (car (cdr (cdr '(a b c))))
         &rArr; c
</pre>
  <p class="noindent">which may be read as:

  <blockquote>
<code>(third '(a b c))</code> expands to <code>(car (cdr (cdr '(a b c))))</code>;
the result of evaluating the expression is <code>c</code>. 
</blockquote>

<p class="noindent">Often, as in this case, an example looks better if the
<code>@expansion{}</code> and <code>@result{}</code> commands are indented.

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texinfo-doc-nonfree 4.13a-1 / usr / share / doc / texinfo / html / expansion.html
