cyclops.async

Class Future.Instances

java.lang.Object

cyclops.async.Future.Instances

Enclosing class:

Future<T>

public static class Future.Instances
extends java.lang.Object

Companion class for creating Type Class instances for working with Futures

Constructor Summary

Constructors

Constructor and Description
Instances()

Method Summary

Modifier and Type	Method and Description
static <T,R> Applicative<Witness.future>	applicative() import static com.aol.cyclops.hkt.jdk.Future.widen; import static com.aol.cyclops.util.function.Lambda.l1; import static java.util.Arrays.asFuture; Futures.zippingApplicative() .ap(widen(asFuture(l1(this::multiplyByTwo))),widen(asFuture(1,2,3))); //[2,4,6]
static <T> Comonad<Witness.future>	comonad()
static InstanceDefinitions<Witness.future>	definitions()
static <T,R> Foldable<Witness.future>	foldable() int sum = Futures.foldable() .foldLeft(0, (a,b)->a+b, Future.widen(Future.ofResult(4))); //4
static <T,R> Functor<Witness.future>	functor() Transform a future, mulitplying every element by 2
static <T,R> Monad<Witness.future>	monad() import static com.aol.cyclops.hkt.jdk.Future.widen; Future<Integer> future = Futures.monad() .flatMap(i->widen(Future.ofResult(0)), widen(Future.ofResult(2))) .convert(Future::narrowK3);
static <T> MonadPlus<Witness.future>	monadPlus() Future<Integer> future = Futures.<Integer>monadPlus() .plus(Future.widen(Future.future()), Future.widen(Future.ofResult(10))) .convert(Future::narrowK3); //Future[10]
static <T> MonadPlus<Witness.future>	monadPlus(Monoid<Future<T>> m) Monoid<Future<Integer>> m = Monoid.of(Future.widen(Future.future()()), (a,b)->a.isDone() ? b : a); Future<Integer> future = Futures.<Integer>monadPlus(m) .plus(Future.widen(Future.ofResult(5)), Future.widen(Future.ofResult(10))) .convert(Future::narrowK3); //Future(5)
static <T,R> MonadRec<Witness.future>	monadRec()
static <T,R> MonadZero<Witness.future>	monadZero() Future<String> future = Futures.unit() .unit("hello") .applyHKT(h->Futures.monadZero().filter((String t)->t.startsWith("he"), h)) .convert(Future::narrowK3); //Future["hello"]
static <C2,T> Traverse<Witness.future>	traverse()
static <T> Pure<Witness.future>	unit() Future<String> future = Futures.unit() .unit("hello") .convert(Future::narrowK3); //Future("hello")

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Instances

public Instances()

Method Detail

definitions

public static InstanceDefinitions<Witness.future> definitions()

functor

public static <T,R> Functor<Witness.future> functor()

Transform a future, mulitplying every element by 2

 
  Future<Integer> future = Futures.functor().map(i->i*2, Future.widen(Future.ofResult(2));

  //[4]


 
 

An example fluent api working with Futures

 
   Future<Integer> future = Futures.unit()
        .unit("hello")
        .applyHKT(h->Futures.functor().map((String v) ->v.length(), h))
        .convert(Future::narrowK3);

 
 

Returns:

A functor for Futures

unit

public static <T> Pure<Witness.future> unit()

 
 Future<String> future = Futures.unit()
        .unit("hello")
        .convert(Future::narrowK3);

        //Future("hello")

 
 

Returns:

A factory for Futures

applicative

public static <T,R> Applicative<Witness.future> applicative()

 
 import static com.aol.cyclops.hkt.jdk.Future.widen;
 import static com.aol.cyclops.util.function.Lambda.l1;
 import static java.util.Arrays.asFuture;

        Futures.zippingApplicative()
        .ap(widen(asFuture(l1(this::multiplyByTwo))),widen(asFuture(1,2,3)));

 //[2,4,6]
 
 

Example fluent API

 
 Future<Function<Integer,Integer>> futureFn =Futures.unit()
                                                  .unit(Lambda.l1((Integer i) ->i*2))
                                                  .convert(Future::narrowK3);

        Future<Integer> future = Futures.unit()
        .unit("hello")
        .applyHKT(h->Futures.functor().map((String v) ->v.length(), h))
        .applyHKT(h->Futures.applicative().ap(futureFn, h))
        .convert(Future::narrowK3);

        //Future("hello".length()*2))

 
 

Returns:

A zipper for Futures

monad

public static <T,R> Monad<Witness.future> monad()

 
 import static com.aol.cyclops.hkt.jdk.Future.widen;
 Future<Integer> future  = Futures.monad()
        .flatMap(i->widen(Future.ofResult(0)), widen(Future.ofResult(2)))
        .convert(Future::narrowK3);
 
 

Example fluent API

 
    Future<Integer> future = Futures.unit()
        .unit("hello")
        .applyHKT(h->Futures.monad().flatMap((String v) ->Futures.unit().unit(v.length()), h))
        .convert(Future::narrowK3);

        //Future("hello".length())

 
 

Returns:

Type class with monad functions for Futures

monadZero

public static <T,R> MonadZero<Witness.future> monadZero()

 
  Future<String> future = Futures.unit()
        .unit("hello")
        .applyHKT(h->Futures.monadZero().filter((String t)->t.startsWith("he"), h))
        .convert(Future::narrowK3);

        //Future["hello"]

 
 

Returns:

A filterable monad (with default value)

monadRec

public static <T,R> MonadRec<Witness.future> monadRec()

monadPlus

public static <T> MonadPlus<Witness.future> monadPlus()

 
  Future<Integer> future = Futures.<Integer>monadPlus()
        .plus(Future.widen(Future.future()), Future.widen(Future.ofResult(10)))
        .convert(Future::narrowK3);
        //Future[10]

 
 

Returns:

Type class for combining Futures by concatenation

monadPlus

public static <T> MonadPlus<Witness.future> monadPlus(Monoid<Future<T>> m)

 
  Monoid<Future<Integer>> m = Monoid.of(Future.widen(Future.future()()), (a,b)->a.isDone() ? b : a);
        Future<Integer> future = Futures.<Integer>monadPlus(m)
        .plus(Future.widen(Future.ofResult(5)), Future.widen(Future.ofResult(10)))
        .convert(Future::narrowK3);
        //Future(5)

 
 

Parameters:

m - Monoid to use for combining Futures

Returns:

Type class for combining Futures

traverse

public static <C2,T> Traverse<Witness.future> traverse()

Returns:

Type class for traversables with traverse / sequence operations

foldable

public static <T,R> Foldable<Witness.future> foldable()

 
 int sum  = Futures.foldable()
        .foldLeft(0, (a,b)->a+b, Future.widen(Future.ofResult(4)));

        //4

 
 

Returns:

Type class for folding / reduction operations

comonad

public static <T> Comonad<Witness.future> comonad()