com.aol.cyclops

Interface Reducer<T>

All Superinterfaces:

java.util.function.BiFunction<T,T,T>, java.util.function.BinaryOperator<T>, Monoid<T>, Semigroup<T>

public interface Reducer<T>
extends Monoid<T>

Method Summary

Modifier and Type	Method and Description
static <T> Reducer<T>	fromMonoid(Monoid<T> monoid, java.util.function.Function<?,? extends T> mapper)
default T	mapReduce(java.util.stream.Stream toReduce) Map a given Stream to required type (via mapToType method), then reduce using this monoid Example of multiple reduction using multiple Monoids and PowerTuples
default java.util.stream.Stream<T>	mapToType(java.util.stream.Stream stream)
static <T> Reducer<T>	of(T zero, java.util.function.BiFunction<T,T,T> combiner, java.util.function.Function<?,? extends T> mapToType)
static <T> Reducer<T>	of(T zero, java.util.function.Function<T,java.util.function.Function<T,T>> combiner, java.util.function.Function<?,T> mapToType)

Methods inherited from interface com.aol.cyclops.Monoid

fromBiFunction, of, of, reduce, zero

Methods inherited from interface com.aol.cyclops.Semigroup

apply, combiner, reducer

Methods inherited from interface java.util.function.BinaryOperator

maxBy, minBy

Methods inherited from interface java.util.function.BiFunction

andThen

Method Detail

mapToType

default java.util.stream.Stream<T> mapToType(java.util.stream.Stream stream)

mapReduce

default T mapReduce(java.util.stream.Stream toReduce)

Map a given Stream to required type (via mapToType method), then reduce using this monoid Example of multiple reduction using multiple Monoids and PowerTuples

 
  Monoid<Integer> sum = Monoid.of(0,(a,b)->a+b);
	Monoid<Integer> mult = Monoid.of(1,(a,b)->a*b);
	<PTuple2<Integer,Integer>> result = PowerTuples.tuple(sum,mult).<PTuple2<Integer,Integer>>asReducer()
										.mapReduce(Stream.of(1,2,3,4)); 
	 
	assertThat(result,equalTo(tuple(10,24)));
  

Parameters:

toReduce - Stream to reduce

Returns:

reduced value

fromMonoid

static <T> Reducer<T> fromMonoid(Monoid<T> monoid,
                                 java.util.function.Function<?,? extends T> mapper)

of

static <T> Reducer<T> of(T zero,
                         java.util.function.BiFunction<T,T,T> combiner,
                         java.util.function.Function<?,? extends T> mapToType)

of

static <T> Reducer<T> of(T zero,
                         java.util.function.Function<T,java.util.function.Function<T,T>> combiner,
                         java.util.function.Function<?,T> mapToType)