https://svn.boost.org/trac10/ticket/6282 <p> code such as the following doesn't work. That is, none of the views can produce a set type sequence. Note this is diffferent from fusion so it is possible. I also realize that this is non-trivial enhancement. Oh well. </p> <pre class="wiki"> struct a {}; struct b {}; struct c {}; struct d {}; typedef boost::mpl::set&lt;a, b, c&gt; s1; BOOST_CONCEPT_ASSERT(( boost::mpl::AssociativeSequence&lt;s1&gt; )); typedef boost::mpl::set&lt;c, d&gt; s2; BOOST_CONCEPT_ASSERT(( boost::mpl::AssociativeSequence&lt;s2&gt; )); typedef boost::mpl::joint_view&lt;s1, s2&gt;::type sdiff; BOOST_CONCEPT_ASSERT(( boost::mpl::AssociativeSequence&lt;sdiff&gt; )); </pre><p> I know it's correct as is - that is it works according to they it's described in the manual. But it was hard to find my mistake. </p> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/6282 Trac 1.4.3