Loose end: zip

Brian Goetz brian.goetz at oracle.com
Thu Jun 6 12:49:05 PDT 2013

Still feeling kind of YAGNI on zip, for the reasons cited in the message 
below, plus:
  - No primitive versions (would require new SAMs)
  - Hard to parallelize
  - Multiple ways to deal with streams of different length; we pick one

Might this be something best provided by some other library than the 
JDK?  Or as a code example somewhere people can crib from to roll their 

On 5/1/2013 5:10 PM, Brian Goetz wrote:
> Right, but the question is, how badly can we implement it and have it
> not be worse than nothing?  And, with the current performance
> characteristics (new object per element), are we below that threshold?
> My problem is the same as with flatMap -- these are idioms from other
> languages that *translate poorly* to Java because of the lack of tuples
> and other structural types.  (The flatMap we got left with -- which I
> reluctantly supported as the lesser of evils -- is, coincidentally, the
> only other stream operation that has allocation-per-element.)  At what
> level of translation-fidelity loss do we say "yeah, it works great in
> that other environment, but too much is lost in translation"?
> I don't doubt the utility of zip, or the fact that Joe-alikes will want
> it, and would be bummed to not find it.  My question is whether the
> crappy zip we can have is better than no zip.  (Where better doesn't
> just mean "better than nothing", but carries its weight.)

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