Yet another run at reduce

[Remi Forax]

On 01/08/2013 06:08 PM, Brian Goetz wrote:
> And then...
>
>   into(collection)
>
> becomes
>
>   reduce(intoList())
>   reduce(intoSet())

I think, I prefer, reduce(toList()) and reduce(toSet()),
because their semantics is slightly different than into.

> reduce(intoCollection(ArrayList::new))
>
> where intoList() could be as simple as:
>
>     public static<T>
>     Reducer<T,List<T>> intoList() {
>         return intoCollection(ArrayList<T>::new);
>     }
>
> and intoCollection is as shown below.

intoCollection should specifies that the supplier can be called several 
times, so it should always returns a new collection, i.e. this doesn't work:
public static<T> Reducer<T,List<T>> intoList() {
     ArrayList<T> list = new ArrayList<>();
     return intoCollection(() -> list);
}

I fear that people will write something like that and only test with a 
serial stream.

>
> Then into() goes away.
>
> Then sequential() goes away.

yes.

Rémi

>
>
>
>
> On 1/8/2013 11:37 AM, Tim Peierls wrote:
>> On Tue, Jan 8, 2013 at 11:18 AM, Brian Goetz <brian.goetz at oracle.com
>> <mailto:brian.goetz at oracle.com>> wrote:
>>
>>     Where intoCollection is a simple Reducer:
>>
>>          Reducer<T,C> intoCollection(Supplier<C> collectionFactory) {
>>              return leftCombiningReducer(__collectionFactory,
>>     Collection::add, Collection::addAll);
>>          }
>>
>>
>> And leftCombiningReducer builds a reducer out of its arguments, which
>> correspond to makeResult, accumulate, and combine?
>>
>> --tim