cpp-lazy-stream/streams/fold.hpp

//
//  fold.hpp
//  stream
//
//  Created by Sam Jaffe on 8/14/16.
//

#pragma once

#include <numeric>

namespace stream {
  template <typename L, typename R>
  struct fold_left_t {
    L init;
    std::function<L(const L&, const R&)> fold;
  };
}

template <typename L, typename R, bool B>
L operator >(stream::detail::stream_base<R, B> const &s, stream::fold_left_t<L, R> && f) {
  return std::accumulate(s.begin(), s.end(), f.fold, f.init);
}