explode (original) (raw)

Brian Goetz brian.goetz at oracle.com
Fri Feb 8 07:47:17 PST 2013

OK, just to put it all down on "paper" where flatMap landed...are we OK with this?

java.util.stream.FlatMapper:

public interface FlatMapper<T, U> { void explodeInto(T element, Consumer sink);

 interface ToInt<T> {
     void explodeInto(T element, IntConsumer sink);
 }

 interface ToLong<T> {
     void explodeInto(T element, LongConsumer sink);
 }

 interface ToDouble<T> {
     void explodeInto(T element, DoubleConsumer sink);
 }

 interface OfIntToInt {
     void explodeInto(int element, IntConsumer sink);
 }

 interface OfLongToLong {
     void explodeInto(long element, LongConsumer sink);
 }

 interface OfDoubleToDouble {
     void explodeInto(double element, DoubleConsumer sink);
 }

}

In Stream:

 <R> Stream<R> flatMap(Function<T, Stream<? extends R>> mapper);

 <R> Stream<R> flatMap(FlatMapper<? super T, R> mapper);

 IntStream flatMap(FlatMapper.ToInt<? super T> mapper);
 LongStream flatMap(FlatMapper.ToLong<? super T> mapper);
 DoubleStream flatMap(FlatMapper.ToDouble<? super T> mapper);

In IntStream (similar for {Double,Long}Stream):

 IntStream flatMap(IntFunction<? extends IntStream> mapper);
 IntStream flatMap(FlatMapper.OfIntToInt mapper);

And Remi wants one more static helper method in FlatMap:

public static <T, U> FlatMapper<T, U> explodeCollection(Function<? super T, ? extends Collection<? extends U>> function)

I think this wraps up the explosive section of our program?

On 2/6/2013 7:05 PM, Kevin Bourrillion wrote:

On Wed, Feb 6, 2013 at 3:30 PM, Brian Goetz <brian.goetz at oracle.com_ _<mailto:brian.goetz at oracle.com>> wrote:

Stream flatMap(FlatMapper<T, U>) Stream flatMap(Function<T, Stream>)

To make sure I understand: would these two behave identically? Would they imaginably perform comparably? foos.stream().flatMap((t, consumer) -> t.somethingThatGivesAStream().forEach(consumer)) foos.stream().flatMap(t -> t.somethingThatGivesAStream()) Second question, why "FlatMapper.OfInt" here, but "IntSupplier" etc. elsewhere? -- Kevin Bourrillion | Java Librarian | Google, Inc. |kevinb at google.com <mailto:kevinb at google.com>

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