Header <hpx/lcos/reduce.hpp>

namespace hpx {
  namespace lcos {
    template<typename Action, typename ReduceOp, typename ArgN, ... > 
      hpx::future< decltype(Action(hpx::id_type, ArgN,...))> 
      reduce(std::vector< hpx::id_type > const &, ReduceOp &&, ArgN, ...);
    template<typename Action, typename ReduceOp, typename ArgN, ... > 
      hpx::future< decltype(Action(hpx::id_type, ArgN,..., std::size_t))> 
      reduce_with_index(std::vector< hpx::id_type > const &, ReduceOp &&, 
                        ArgN, ...);
  }
}