Example

The STL find algorithm looks for the first element in a list with value = value. It is written as follows:

 template <class InputIterator, class T>

		InputIterator find(InputIterator first,

								InputIterator last,

								const T& value)

		 {

				    while (first != last && *first != value)

				 {

						      ++first;

				    }

				    return first;

		}

The following code fragment builds a list of future computations and executes find() over this list to find the first element in the list with a zero value.

 int foo(const int i);

		typedef Future<int> future_type;

		typedef list<future_type> list_type;

		list_type xlist;

		for(int i = 0; i < N; i++)

				 xlist.push_back(future_type(foo, i)); // add to list

		

		list_type::iterator pos

				 = find(xlist.begin(), xlist.end(), 0);

Here find computes only to the point where it finds an element with a value = value. The remaining futures need not even be computed or resolved.