Remove cumulate from Stream interface

[Remi Forax]

On 12/05/2012 07:55 PM, Brian Goetz wrote:
>>> Plus, your Mapper will violate the to-be-written specs about
>>> statefulness/side-effects in lambdas passed to functional stream 
>>> methods.
>>
>> Do you really want this overly restrictive wording for streams that are
>> sequential ?
>> I find this unrealistic, even if you try to specify this in the doc,
>> nobody read the doc if not forced.
>> Given that will not be enforced in the code, it will be only true on the
>> paper.
>
> It may be unrealistic, but we have to do it anyway.  If someone passes 
> a Function to map() that mutates the collection source, all bets are 
> going to be off, and we have to say this.

yes, but mutating the collection source is not the same as saying no 
side effect.
Moreover, i have trouble to understand why the old rules can't be 
applied for serial stream. If the collection is a concurrent collection, 
there is no problem, . If the collection is not concurrent, it will 
fail-fast.

For parallel stream, if the lambda have side effects, i agree that there 
is no guarantee.

>   The spec can characterize when things are guaranteed to work; if 
> people do things that accidentally work because they are operating in 
> a restrictive environment, that's their concern.
>

that why I think that sequential stream should always work or get a 
fail-fast exception and parallel stream should only work for lambda with 
no side effect.

Rémi