Header file algorithms/index_of.hpp

namespace brigand
{
    template <class Sequence, class Predicate, class NotFoundType = no_such_type_>
    using index_if = typename detail::index_if_impl<::brigand::found<Sequence, Predicate>::value, Sequence, Predicate, NotFoundType>::type;
    
    template <class Sequence, typename T>
    using index_of = index_if<Sequence, std::is_same<T,::brigand::_1>>;
}