Hi, As some might know, I'm currently working on a reimplementation of the MPL for C++11. In doing so, I came across a technique that I did not know of and I thought I would share my discovery with the community. If this is already well known, please excuse my ignorance. The goal is to implement fast compile-time conjunction and disjunction. It goes like this: template <typename ...T> void allow_expansion(T&&...); template <typename ...T> struct or_ { static constexpr bool value = !noexcept( allow_expansion((T::value ? throw : 0)...) ); }; That's it! Note that disjunction is easily obtained in a similar way. The benefit of this technique over traditional implementations is that it's several times faster according to my benchmarks. However, you might have noticed that short-circuit evaluation is not respected so the above technique is only suitable when short-circuit evaluation is not required. If you find this interesting, see [1] for a collection of similar techniques. The one I posted above seems to be the fastest with Clang and GCC. Regards, Louis Dionne [1] https://gist.github.com/ldionne/7522393