include &lt;<a class="code" href="optional_8hpp.html">boost/hana/optional.hpp</a>&gt;</span></div>
<div class="line"><span class="preprocessor">#include &lt;<a class="code" href="type_8hpp.html">boost/hana/type.hpp</a>&gt;</span></div>
<div class="line"> </div>
<div class="line"><span class="preprocessor">#include &lt;<a class="code" href="boost_2mpl_2vector_8hpp.html">boost/mpl/vector.hpp</a>&gt;</span></div>
<div class="line"><span class="keyword">namespace </span>hana = <a class="code" href="namespaceboo