Stream of infinite number of elements

[Brian Goetz]

Yes we did!

On 12/30/2012 10:55 AM, Daniel Kristensen wrote:
> Hi,
>
> Did you consider pushing the strict operations to a sub-interface of
> Stream. A few examples of where methods would go:
>
> public interface Stream<T> extends BaseStream<T> {
>
>      Stream<T> filter(Predicate<? super T> predicate);
>
>      <R> Stream<R> map(Mapper<? extends R, ? super T> mapper);
>
>      ...
>
>      FiniteStream<T> limit(int n);
>
>      ...
>
> }
>
>
> public interface FiniteStream<T> extends Stream<T> {
>
>      FiniteStream<T> sorted(Comparator<? super T> comparator);
>
>      void forEach(Block<? super T> block);
>
>      <A extends Destination<? super T>> A into(A target);
>
>      Object[] toArray();
>
>      ...
>
> }
>
>
> This would increase type safety, and would remove the needto document
> in javadoc whether methods that take streams as parameters require
> them to be finite etc.
>
>
> Of course a drawback would be that FiniteStream is not quite as nicely
> succinct as Stream.
>
>
> Best regards
>
> Daniel
>
>
>
>
>> Message: 6
>> Date: Fri, 28 Dec 2012 17:14:12 +0100
>> From: Paul Sandoz <paul.sandoz at oracle.com>
>> Subject: Re: Stream of infinite number of elements
>> Cc: lambda-dev at openjdk.java.net
>> Message-ID: <BFF9D2A3-DF34-4C71-95FC-BD658AC8EE4D at oracle.com>
>> Content-Type: text/plain; charset=us-ascii
>>
>> On Dec 26, 2012, at 3:23 PM, Denis DEBARBIEUX <denis.debarbieux at inria.fr>
>> wrote:
>>> Hi all,
>>>
>>> To implement the interface /Stream/, I have to implement methods like
>>> /max, min, sorted/.
>>>
>>> What is expected by the interface when my stream is infinite?
>> Undetermined behaviour, unless those terminal operations are prefixed with
>> an intermediate limit operation.
>> The first two might never return and the latter one will most likely throw
>> an OOE.
>>
>>> Throw an
>>> exception (does the interface provide an InfiniteStreamException?) or
>>> implement them as an any time algorithm?
>>>
>> We are considering a cancel or while operation that on say a met temporal
>> condition will ensure no more elements are available, thus
>> non-short-circuit terminal operations should terminate under such
>> conditions.
>> Originally we tried to detect cases when an infinite stream was hooked up
>> to something that would be known to not terminate but we cannot capture all
>> such cases so rather than partially supporting this we decided to go for
>> the "developer beware" option.
>> Paul.
>