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<span id="g_t_0040expansion"></span><div class="header">
<p>
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<span id="g_t_0040expansion_007b_007d-_0028_21a6_0029_003a-Indicating-an-Expansion"></span><h4 class="subsection">12.9.3 <code>@expansion{}</code> (→): Indicating an Expansion</h4>
<span id="expansion"></span><span id="index-Expansion_002c-indicating"></span>
<span id="index-Macro-expansion_002c-indicating"></span>
<span id="index-expansion"></span>
<p>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>
<p>The <code>@expansion{}</code> command is displayed as
‘<samp>→</samp>’, either a long arrow with a flat base or (when
that is not available) the ASCII sequence ‘<samp>==></samp>’.
</p>
<p>For example, the following
</p>
<div class="example">
<pre class="example">@lisp
(third '(a b c))
@expansion{} (car (cdr (cdr '(a b c))))
@result{} c
@end lisp
</pre></div>
<p>produces
</p>
<div class="lisp">
<pre class="lisp">(third '(a b c))
→ (car (cdr (cdr '(a b c))))
⇒ c
</pre></div>
<p>which may be read as:
</p>
<blockquote>
<p><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>.
</p></blockquote>
<p>Often, as in this case, an example looks better if the
<code>@expansion{}</code> and <code>@result{}</code> commands are indented.
</p>
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