Extending Collector to handle a post-transform

Tim Peierls tim at peierls.net
Tue Jun 11 10:22:06 PDT 2013

On Tue, Jun 11, 2013 at 1:04 PM, Brian Goetz <brian.goetz at oracle.com> wrote:

> 1.  Reducing boxing during reducing.  Currently, the reducing collectors
> will unbox, compute a new result, and rebox, on every element.  That ugly
> and slow.  With a post-transform, we can use a hidden mutable holder as our
> internal representation, and still only expose "Collector from T to Long".

Nice, indeed, but won't the internal type still appear as a type parameter
of Collector?

2.  By dialing back on the accumulator function's choice of operating
> functionally or ability to produce a new value (which was really only
> required by reduce), we can get rid of the characteristic STRICTLY_MUTATIVE
> which introduces complexity into the API and implementation.

Also nice.

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