t::filter</code> now no longer accept variadic template parameters. Wrap variadic parameters in a type_list. (Allowing both <code>type_list&lt;Ts...&gt;</code> and <code>Ts...</code> is problematic due to cryptic errors when e.g. <code>const type_list&lt;Ts...&gt;</code> is provided.)</li>
<li>Breaking change: <code>util::accumulate</code> now mimics the behaviour of <code>std::accumulate</code> more closely. It relies on the return value of the functor instead of mutating the accumulator argument. The new 