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<title>Logtalk control construct: {}/1</title>
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<div class="top-left">Logtalk reference manual</div>
<div class="top-right">Control construct: {}/1</div>
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<h2 id="control_external1" class="codenp">{}/1</h2>
<h4>Description</h4>
<pre>{Goal}</pre>
<p>
Calls external Prolog code. Can be used to bypass the Logtalk compiler. The argument is called within the context of the pseudo-object <em>user</em>.
</p>
<h4>Template and modes</h4>
<pre>{+callable}</pre>
<h4>Errors</h4>
<dl>
<dt>Goal is a variable:</dt>
<dd><code>instantiation_error</code></dd>
<dt>Goal is neither a variable nor a callable term:</dt>
<dd><code>type_error(callable, Goal)</code></dd>
</dl>
<h4>Examples</h4>
<pre>N1/D1 &lt; N2/D2 :-
{N1*D2 &lt; N2*D1}.</pre>
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<span>Copyright &copy; <a href="mailto:pmoura@logtalk.org">Paulo Moura</a> &mdash; <a href="http://logtalk.org">Logtalk.org</a></span><br/>
<span>Last updated on: June 5, 2007</span>
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