"Cancelable" streams

[Remi Forax]

On 12/08/2012 11:54 PM, Brian Goetz wrote:
>>> Parallel limit has some serious limitations that make it pretty
>>> unsuitable for this case.  While these may be fixable, the effort and
>>> distortion involved is far, far greater than what is being suggested
>>> here.  In fact, I'm on the fence about whether to keep limit at all in
>>> its current state; I worry people will expect more of it than it can
>>> deliver, and be unhappy.
>>
>> I don't get it. You can check the limit the very same way you want to
>> check shouldCancel.
>
> Only in the serial case (easy) or in the parallel case where we know 
> that we don't have to respect encounter order.  But in the general 
> case, encounter order is significant (consider a reduce with an 
> associative but not commutative reducing function), you can't just 
> send the first N that you happen to find through. limit(n) must send 
> the first N in the *encounter order* in this case.  This is where the 
> pain and complexity comes from.
>

that's why we have unordered()

Rémi