sum return type for primitive streams

[Kevin Bourrillion]

The sum of no values is mathematically well-defined (zero); the others are
not.


On Fri, Feb 1, 2013 at 6:43 AM, Georgiy Rakov <georgiy.rakov at oracle.com>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.
>
> Thank you, Georgiy.
>
>


-- 
Kevin Bourrillion | Java Librarian | Google, Inc. | kevinb at google.com