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<title>Logtalk built-in predicate: retractall/1</title>
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<h2><code>retractall/1</code></h2>
<h4>Description</h4>
<blockquote>
<pre>retractall(Head)</pre>
<p>
Logtalk adds this built-in predicate, with the usual definition, to a Prolog compiler if it is not already defined.
</p>
</blockquote>
<h4>Template and modes</h4>
<pre>retractall(+callable)</pre>
<h4>Errors</h4>
<dl>
<dt>Head is not a callable term:</dt>
<dd><code>type_error(callable, Head)</code></dd>
</dl>
<h4>Examples</h4>
<pre>| ?- retractall(foo(_)).</pre>
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