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<title>avram - a virtual machine code interpreter: 2.7.7.2 Note</title>

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<a name="Note-1"></a>
<h4 class="subsubsection">2.7.7.2 Note</h4>

<p>This operation allows arbitrary information or comments to be embedded
in a virtual code application in such a way that it will be ignored by
<code>avram</code> when executing it. For the <code>silly</code> language, a
<code>note</code> function is defined in the standard prelude so as to imply
the following theorem.
<a name="index-note"></a>
<a name="index-annotations"></a>
</p>
<dl compact="compact">
<dt> <em>T11</em></dt>
<dd><p>[[<code>note</code>]] <code>(<var>f</var>,<var>c</var>)</code> = <code>((nil,nil),((nil,nil),(nil,(nil,(<var>f</var>,<var>c</var>)))))</code>
</p></dd>
</dl>

<p>Intuitively, the argument <code><var>f</var></code> represents a function, and the
argument <code>c</code> represents the comment, annotation, or whatever, that
will be embedded but ignored in the virtual code.
</p>
<p>Semantically, a function with a note attached is the same as the
function by itself, as the following property stipulates for
any non-<code>nil</code> <code><var>f</var></code>.
</p>
<dl compact="compact">
<dt> <em>P8</em></dt>
<dd><p>([[<code>note</code>]] <code>(<var>f</var>,<var>c</var>)</code>) <code><var>x</var></code> = <code><var>f</var> <var>x</var></code>
</p></dd>
</dl>

<p>A possible reason for using this feature might be to support a language
that performs run-time type checking by hanging type tags on
<a name="index-type-tags"></a>
everything. Another possible use would be to include symbolic
information needed by a debugger.
</p>
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