oreign-dyn</code>, <code>expand-to-foreign</code> and
<code>expand-from-foreign</code>. Here's how one could define a
<code>my-boolean</code> with them:

<pre class="lisp">  <span class="paren1">(<span class="lisp-bg"><i><span class="symbol">define-foreign-type</span></i> my-boolean-type <span class="paren2">(<span class="lisp-bg"></span>)</span>
    <span class="paren2">(<span class="lisp-bg"></span>)</span>
    <span class="paren2">(<span class="lisp-bg"><span class="keyword">:actual-type</span> <span cla