Reducing reduce

[Paul Sandoz]

On Feb 11, 2013, at 6:12 PM, Brian Goetz <brian.goetz at Oracle.COM> wrote:

> Thanks, Joe.  I knew I was missing some use cases.  This is definitely a case where the fused version is more efficient, since it can elide some work based on the previous comparison state.
> 

And efficiency wise it would be nice to avoid the boxed().

Paul.

> On 2/11/2013 11:57 AM, Joe Bowbeer wrote:
>> My parallel string-compare sample provides two implementations (below).
>> 
>> Will both of these survive your changes?
>> 
>> bitbucket.org/joebowbeer/stringcompare
>> <http://bitbucket.org/joebowbeer/stringcompare>
>> 
>>   int  compareMapReduce(String  s1,  String  s2)  {
>>     assert  s1.length()  ==  s2.length();
>>     return  intRange(0,  s1.length()).parallel()
>>         .map(i  ->  compare(s1.charAt(i),  s2.charAt(i)))
>>         .reduce(0,  (l,  r)  ->  (l  !=  0)  ?  l  :  r);
>>   }
>> 
>>   int  compareBoxedReduce(String  s1,  String  s2)  {
>>     assert  s1.length()  ==  s2.length();
>>     return  intRange(0,  s1.length()).parallel().boxed()
>>         .reduce(0,  (l,  i)  ->  (l  !=  0)  ?  l  :  compare(s1.charAt(i),  s2.charAt(i)),
>>                    (l,  r)  ->  (l  !=  0)  ?  l  :  r);
>>   }
>>