...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::proto::result_of::flatten — Metafunction that computes the return type of
proto::flatten()
// In header: <boost/proto/fusion.hpp> template<typename Expr> struct flatten { // types typedef unspecified type; // A Fusion Forward Sequence };