//! deep comparison. Hence, we adopt a conservative stance and avoid
//! providing comparison for `Metafunction`s.
//!
- //! [1]: http://en.cppreference.com/w/cpp/concept/FunctionObject
+ //! [1]: http://en.cppreference.com/w/cpp/named_req/FunctionObject
//! [2]: http://www.boost.org/doc/libs/release/libs/mpl/doc/refmanual/metafunction-class.html
template <typename F>
struct Metafunction;