Using Oliver Kowalke's coroutines headers which will soon be in Boost

gistfile1.cpp

//https://gitorious.org/boost-dev/boost-dev, coroutine branch
//g++ -I path/to/boost-dev -std=c++11 code.cpp -static -L path/to/boost-dev/stage/lib/ -lboost_context

#include <boost/coroutine/all.hpp>
#include <boost/bind.hpp>
#include <boost/range.hpp>
#include <iostream>
#include <vector>

using namespace std;
using namespace boost;

template <typename T>
using coro_pairT_void = coroutines::coroutine<pair<T&,T&>(void)>;

template <typename T>
void combinations(typename coro_pairT_void<T>::caller_type & self, vector<T> & input ) { 
  for (auto it1 = input.begin(), itend = input.end(); it1 != itend; it1++) {
    for (auto it2 = std::next(it1); it2 != itend; it2++) {
      self(pair<T&, T&>(*it1,*it2));
    }   
  }
};

int main( void ) { 
  vector<int> numbers{1,2,3,4,5,6};
  coro_pairT_void<int> func(bind(combinations<int>, _1, numbers));
  for (auto it(begin(func)), itend(end(func)); it != itend; ++it) {
    cout << it->first << ',' << it->second << endl;
  }
  return 0;
};