sum return type for primitive streams

[Peter Levart]

On 02/01/2013 03:43 PM, Georgiy Rakov wrote:
> Hello,
>
> IntStream sum method return type is a primitive while the return type of
> min, max, average is Optional...:
>
>           default long sum() {
>               return collect(Collectors.intSumAsLong()).sum();
>           }
>
>           default OptionalInt min() {
>               return reduce(Math::min);
>           }
>
>           default OptionalInt max() {
>               return reduce(Math::max);
>           }
>
>           default OptionalDouble average() {
>               return collect(Collectors.intCountAndSumAsLong()).mean();
>           }
>
> Could you please tell if it's a bug or expected behavior. If it's
> expected behavior could you please clarify why it is because from the
> first glance OptionalLong should be the return type for sum method.
>
> The same is true for DoubleStream and LongStream.
Hi Georgiy,

http://en.wikipedia.org/wiki/Empty_sum

According to above, even the return type of average() could be double 
(not OptionalDouble)...

Regards, Peter

>
> Thank you, Georgiy.
>