var promise = new Promise<string>((fulfill, failure) => 
{
  var response, error = API.Call("");
  if (error != null)
  {
    failure(error);
  }
  else 
  {
    fulfill(response);
  }
});

Promise<int> promise = Promise.Of(3);

Promise<int> promise = Promise.Pending<int>();
if (pass)
  promise.Fullfil(3);
else
  promise.Reject(new Exception());

Promise.Of(3)
  .Then(x => x++)
  .Then(x => x++)
  .Then(x => x++);