"line">};</div><div class="line"></div><div class="line"><span class="comment">// The keys can be anything as long as they are compile-time comparable.</span></div><div class="line">constexpr <span class="keyword">auto</span> name = hana::integral_c&lt;std::string Person::*, &amp;Person::name&gt;;</div><div class="line">constexpr <span class="keyword">auto</span> age = hana::string_c&lt;&#39;a&#39;, &#39;g&#39;, &#39;e&#39;&gt;;</div><div class="line"></div><div class="line"><span class="keyword">namespace 