gistfile1.cpp

#include <map>
#include <vector>
#include <string>
#include <future>
#include <boost/lexical_cast.hpp>

using namespace std;
using boost::lexical_cast;

typedef map<string, string> object;

vector<object> objects = { 
    {{"user", "kyle"}, {"amount", "42"}},
    {{"user", "kyle"}, {"amount", "1"}},
    {{"user",  "andy"}, {"amount", "0"}}
};

int main(void) { 
    cout << async([]() { 
                int sum;
                for (object o: objects) 
                    if (o["user"] == "kyle") 
                        sum += lexical_cast<int>(o["amount"]);
                return sum;
        }).get() << endl;
    return 0;
}