accumulate if?

#include <functional>
#include <iostream>
#include <numeric>
 
 
template<typename _InIt, typename _Ty, typename _Func1, typename _Func2>
_Ty accumulate_if(_InIt _First, _InIt _Last, _Ty _Val, _Func1 F1, _Func2 F2){
    for(; _First != _Last; ++_First)
        if( F2(*_First) )
            _Val = F1(_Val, *_First); 
    return _Val;
}
 
 
int main()
{
 
    int arr[10] = {-5, -4, -3, -2, -1, 1, 2, 3, 4, 5};
 
    std::cout 
        << accumulate_if(arr, arr + 10, 0, std::plus<int>(), std::bind2nd(std::greater<int>(), 0))
        << std::endl;
    return 0;
}

template<class InputIterator, class Type, class BinaryOperation>
   Type accumulate(
      InputIterator _First, 
      InputIterator _Last, 
      Type _Val, 
      BinaryOperation _Binary_op
   );

int SumPositive(int result, int value)
{
    return (value>0) ? (result+value) : result;
}
 
void Foo()
{
    std::list<int> mylist;
...
    int sum_positive = std::accumulate(mylist.begin(), mylist.end(), 0, SumPositive);
}