public static class Optionals.Instances
extends java.lang.Object
Constructor and Description |
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Instances() |
Modifier and Type | Method and Description |
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static <T,R> Applicative<OptionalKind.µ> |
applicative()
import static com.aol.cyclops.hkt.jdk.OptionalKind.widen;
import static com.aol.cyclops.util.function.Lambda.l1;
import static java.util.Arrays.asOptional;
Optionals.zippingApplicative()
.ap(widen(asOptional(l1(this::multiplyByTwo))),widen(asOptional(1,2,3)));
//[2,4,6]
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static <T> Comonad<OptionalKind.µ> |
comonad() |
static <T> Foldable<OptionalKind.µ> |
foldable()
int sum = Optionals.foldable()
.foldLeft(0, (a,b)->a+b, OptionalKind.widen(Arrays.asOptional(1,2,3,4)));
//10
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static <T,R> Functor<OptionalKind.µ> |
functor()
Transform a list, mulitplying every element by 2
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static <T,R> Monad<OptionalKind.µ> |
monad()
import static com.aol.cyclops.hkt.jdk.OptionalKind.widen;
OptionalKind<Integer> list = Optionals.monad()
.flatMap(i->widen(OptionalX.range(0,i)), widen(Arrays.asOptional(1,2,3)))
.convert(OptionalKind::narrowK);
|
static <T> MonadPlus<OptionalKind.µ> |
monadPlus()
OptionalKind<Integer> list = Optionals.<Integer>monadPlus()
.plus(OptionalKind.widen(Arrays.asOptional()), OptionalKind.widen(Arrays.asOptional(10)))
.convert(OptionalKind::narrowK);
//Arrays.asOptional(10))
|
static <T> MonadPlus<OptionalKind.µ> |
monadPlus(Monoid<OptionalKind<T>> m)
Monoid<OptionalKind<Integer>> m = Monoid.of(OptionalKind.widen(Arrays.asOptional()), (a,b)->a.isEmpty() ? b : a);
OptionalKind<Integer> list = Optionals.<Integer>monadPlus(m)
.plus(OptionalKind.widen(Arrays.asOptional(5)), OptionalKind.widen(Arrays.asOptional(10)))
.convert(OptionalKind::narrowK);
//Arrays.asOptional(5))
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static <T,R> MonadZero<OptionalKind.µ> |
monadZero()
OptionalKind<String> list = Optionals.unit()
.unit("hello")
.transform(h->Optionals.monadZero().filter((String t)->t.startsWith("he"), h))
.convert(OptionalKind::narrowK);
//Arrays.asOptional("hello"));
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static <C2,T> Traverse<OptionalKind.µ> |
traverse() |
static <T> Pure<OptionalKind.µ> |
unit()
OptionalKind<String> list = Optionals.unit()
.unit("hello")
.convert(OptionalKind::narrowK);
//Arrays.asOptional("hello"))
|
public static <T,R> Functor<OptionalKind.µ> functor()
OptionalKind<Integer> list = Optionals.functor().map(i->i*2, OptionalKind.widen(Arrays.asOptional(1,2,3));
//[2,4,6]
An example fluent api working with Optionals
OptionalKind<Integer> list = Optionals.unit()
.unit("hello")
.transform(h->Optionals.functor().map((String v) ->v.length(), h))
.convert(OptionalKind::narrowK);
public static <T> Pure<OptionalKind.µ> unit()
OptionalKind<String> list = Optionals.unit()
.unit("hello")
.convert(OptionalKind::narrowK);
//Arrays.asOptional("hello"))
public static <T,R> Applicative<OptionalKind.µ> applicative()
import static com.aol.cyclops.hkt.jdk.OptionalKind.widen;
import static com.aol.cyclops.util.function.Lambda.l1;
import static java.util.Arrays.asOptional;
Optionals.zippingApplicative()
.ap(widen(asOptional(l1(this::multiplyByTwo))),widen(asOptional(1,2,3)));
//[2,4,6]
Example fluent API
OptionalKind<Function<Integer,Integer>> listFn =Optionals.unit()
.unit(Lambda.l1((Integer i) ->i*2))
.convert(OptionalKind::narrowK);
OptionalKind<Integer> list = Optionals.unit()
.unit("hello")
.transform(h->Optionals.functor().map((String v) ->v.length(), h))
.transform(h->Optionals.applicative().ap(listFn, h))
.convert(OptionalKind::narrowK);
//Arrays.asOptional("hello".length()*2))
public static <T,R> Monad<OptionalKind.µ> monad()
import static com.aol.cyclops.hkt.jdk.OptionalKind.widen;
OptionalKind<Integer> list = Optionals.monad()
.flatMap(i->widen(OptionalX.range(0,i)), widen(Arrays.asOptional(1,2,3)))
.convert(OptionalKind::narrowK);
Example fluent API
OptionalKind<Integer> list = Optionals.unit()
.unit("hello")
.transform(h->Optionals.monad().flatMap((String v) ->Optionals.unit().unit(v.length()), h))
.convert(OptionalKind::narrowK);
//Arrays.asOptional("hello".length())
public static <T,R> MonadZero<OptionalKind.µ> monadZero()
OptionalKind<String> list = Optionals.unit()
.unit("hello")
.transform(h->Optionals.monadZero().filter((String t)->t.startsWith("he"), h))
.convert(OptionalKind::narrowK);
//Arrays.asOptional("hello"));
public static <T> MonadPlus<OptionalKind.µ> monadPlus()
OptionalKind<Integer> list = Optionals.<Integer>monadPlus()
.plus(OptionalKind.widen(Arrays.asOptional()), OptionalKind.widen(Arrays.asOptional(10)))
.convert(OptionalKind::narrowK);
//Arrays.asOptional(10))
public static <T> MonadPlus<OptionalKind.µ> monadPlus(Monoid<OptionalKind<T>> m)
Monoid<OptionalKind<Integer>> m = Monoid.of(OptionalKind.widen(Arrays.asOptional()), (a,b)->a.isEmpty() ? b : a);
OptionalKind<Integer> list = Optionals.<Integer>monadPlus(m)
.plus(OptionalKind.widen(Arrays.asOptional(5)), OptionalKind.widen(Arrays.asOptional(10)))
.convert(OptionalKind::narrowK);
//Arrays.asOptional(5))
m
- Monoid to use for combining Optionalspublic static <C2,T> Traverse<OptionalKind.µ> traverse()
public static <T> Foldable<OptionalKind.µ> foldable()
int sum = Optionals.foldable()
.foldLeft(0, (a,b)->a+b, OptionalKind.widen(Arrays.asOptional(1,2,3,4)));
//10
public static <T> Comonad<OptionalKind.µ> comonad()