Option (core 4.8.1 API)

java.lang.Object
- fj.data.Option<A>

All Implemented Interfaces:

java.lang.Iterable<A>
```
public abstract class Option<A>
extends java.lang.Object
implements java.lang.Iterable<A>
```
An optional value that may be none (no value) or some (a value). This type is a replacement for the use of null with better type checks.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class Option.Optic

Nested Classes
Modifier and Type	Class and Description
`static class`	`Option.Optic`

Field Summary

Fields
Modifier and Type	Field and Description
`static F<java.lang.String,Option<java.lang.Byte>>`	`parseByte` A function that parses a string to a byte.
`static F<java.lang.String,Option<java.lang.Double>>`	`parseDouble` A function that parses a string to a double.
`static F<java.lang.String,Option<java.lang.Float>>`	`parseFloat` A function that parses a string to a float.
`static F<java.lang.String,Option<java.lang.Integer>>`	`parseInt` A function that parses a string to an integer.
`static F<java.lang.String,Option<java.lang.Long>>`	`parseLong` A function that parses a string to a long.
`static F<java.lang.String,Option<java.lang.Short>>`	`parseShort` A function that parses a string to a short.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`<B> Option<B>`	`apply(Option<F<A,B>> of)` Performs function application within an optional value (applicative functor pattern).
`A[]`	`array(java.lang.Class<A[]> c)` Returns an array from this optional value.
`static <A,B> F<F<A,Option<B>>,F<Option<A>,Option<B>>>`	`bind()` First-class bind function.
`<B> Option<B>`	`bind(F<A,Option<B>> f)` Binds the given function across the element of this optional value with a final join.
`<B,C> Option<C>`	`bind(Option<B> ob, F<A,F<B,C>> f)` Binds the given function across the element of this optional value and the given optional value with a final join.
`<B,C,D> Option<D>`	`bind(Option<B> ob, Option<C> oc, F<A,F<B,F<C,D>>> f)` Binds the given function across the element of this optional value and the given optional value with a final join.
`<B,C,D,E> Option<E>`	`bind(Option<B> ob, Option<C> oc, Option<D> od, F<A,F<B,F<C,F<D,E>>>> f)` Binds the given function across the element of this optional value and the given optional value with a final join.
`<B,C,D,E,F$> Option<F$>`	`bind(Option<B> ob, Option<C> oc, Option<D> od, Option<E> oe, F<A,F<B,F<C,F<D,F<E,F$>>>>> f)` Binds the given function across the element of this optional value and the given optional value with a final join.
`<B,C,D,E,F$,G> Option<G>`	`bind(Option<B> ob, Option<C> oc, Option<D> od, Option<E> oe, Option<F$> of, F<A,F<B,F<C,F<D,F<E,F<F$,G>>>>>> f)` Binds the given function across the element of this optional value and the given optional value with a final join.
`<B,C,D,E,F$,G,H> Option<H>`	`bind(Option<B> ob, Option<C> oc, Option<D> od, Option<E> oe, Option<F$> of, Option<G> og, F<A,F<B,F<C,F<D,F<E,F<F$,F<G,H>>>>>>> f)` Binds the given function across the element of this optional value and the given optional value with a final join.
`<B,C,D,E,F$,G,H,I> Option<I>`	`bind(Option<B> ob, Option<C> oc, Option<D> od, Option<E> oe, Option<F$> of, Option<G> og, Option<H> oh, F<A,F<B,F<C,F<D,F<E,F<F$,F<G,F<H,I>>>>>>>> f)` Binds the given function across the element of this optional value and the given optional value with a final join.
`<B> Option<P2<A,B>>`	`bindProduct(Option<B> ob)`
`<B,C> Option<P3<A,B,C>>`	`bindProduct(Option<B> ob, Option<C> oc)`
`<B,C,D> Option<P4<A,B,C,D>>`	`bindProduct(Option<B> ob, Option<C> oc, Option<D> od)`
`<B,C,D,E> Option<P5<A,B,C,D,E>>`	`bindProduct(Option<B> ob, Option<C> oc, Option<D> od, Option<E> oe)`
`<B,C,D,E,F$> Option<P6<A,B,C,D,E,F$>>`	`bindProduct(Option<B> ob, Option<C> oc, Option<D> od, Option<E> oe, Option<F$> of)`
`<B,C,D,E,F$,G> Option<P7<A,B,C,D,E,F$,G>>`	`bindProduct(Option<B> ob, Option<C> oc, Option<D> od, Option<E> oe, Option<F$> of, Option<G> og)`
`<B,C,D,E,F$,G,H> Option<P8<A,B,C,D,E,F$,G,H>>`	`bindProduct(Option<B> ob, Option<C> oc, Option<D> od, Option<E> oe, Option<F$> of, Option<G> og, Option<H> oh)`
`boolean`	`equals(java.lang.Object other)`
`boolean`	`exists(F<A,java.lang.Boolean> f)` Returns `true` is this optional value has a value and the given predicate function holds on that value, `false` otherwise.
`Option<A>`	`filter(F<A,java.lang.Boolean> f)` Filters elements from this optional value by returning only elements which produce `true` when the given function is applied to them.
`boolean`	`forall(F<A,java.lang.Boolean> f)` Returns `true` if this optional value has no value, or the predicate holds for the given predicate function, `false` otherwise.
`Unit`	`foreach(F<A,Unit> f)` Performs a side-effect for the value of this optional value.
`void`	`foreachDoEffect(Effect1<A> f)` Performs a side-effect for the value of this optional value.
`static <T> F<T,Option<T>>`	`fromNull()` Turns an unsafe nullable value into a safe optional value.
`static <T> Option<T>`	`fromNull(T t)` Turns an unsafe nullable value into a safe optional value.
`static <A> F<Option<A>,A>`	`fromSome()` Returns a function that takes an optional value to a value or errors if there is no value.
`static F<java.lang.String,Option<java.lang.String>>`	`fromString()` Returns a function that transforms a string to an optional non-empty string, or no value if the string is empty.
`static Option<java.lang.String>`	`fromString(java.lang.String s)` Returns an optional non-empty string, or no value if the given string is empty.
`int`	`hashCode()`
`static <A> F2<F<A,java.lang.Boolean>,A,Option<A>>`	`iif()` First-class version of the iif function.
`static <A> Option<A>`	`iif(boolean p, A a)` Returns an optional value that has a value of the given argument if the given boolean is true, otherwise, returns no value.
`static <A> Option<A>`	`iif(boolean p, F0<A> a)` Returns an optional value that has a value of the given argument if the given boolean is true, otherwise, returns no value.
`static <A> Option<A>`	`iif(F<A,java.lang.Boolean> f, A a)` Returns an optional value that has a value of the given argument, if the given predicate holds on that argument, otherwise, returns no value.
`static <A> F<Option<A>,java.lang.Boolean>`	`isNone_()` A first-class version of the isNone method.
`boolean`	`isNone()` Returns `false` if this optional value has a value, `true` otherwise.
`static <A> F<Option<A>,java.lang.Boolean>`	`isSome_()` A first-class version of the isSome method.
`boolean`	`isSome()` Returns `true` if this optional value has a value, `false` otherwise.
`java.util.Iterator<A>`	`iterator()` Returns an iterator for this optional value.
`static <A> F<Option<Option<A>>,Option<A>>`	`join()` First-class join function.
`static <A> Option<A>`	`join(Option<Option<A>> o)` Joins the given optional value of optional value using a bind operation.
`int`	`length()` Returns the length of this optional value; 1 if there is a value, 0 otherwise.
`static <A,B,C> F<Option<A>,F<Option<B>,Option<C>>>`	`liftM2(F<A,F<B,C>> f)` Promotes a function of arity-2 so that it operates over options.
`<B,C> Option<C>`	`liftM2(Option<B> ob, F2<A,B,C> f)` Lift the function of arity-2 through options.
`static <A,B> F<F<A,B>,F<Option<A>,Option<B>>>`	`map()` A first-class map function.
`<B> Option<B>`	`map(F<A,B> f)` Maps the given function across this optional value.
`static <T> F<T,Option<T>>`	`none_()`
`static <T> Option<T>`	`none()` Constructs an optional value that has no value.
`static <A,B> F<Option<A>,B>`	`option_(B none, F<A,B> some)` First-class catamorphism for Option: return a function that will performs a reduction on an optional value using the given arguments.
`<B> B`	`option(B b, F<A,B> f)` Performs a reduction on this optional value using the given arguments.
`<B> B`	`option(F0<B> b, F<A,B> f)` Performs a reduction on this optional value using the given arguments.
`Option<A>`	`orElse(F0<Option<A>> o)` Returns this optional value if there is one, otherwise, returns the argument optional value.
`Option<A>`	`orElse(Option<A> o)` Returns this optional value if there is one, otherwise, returns the argument optional value.
`A`	`orSome(A a)` Returns the value of this optional value or the given argument.
`A`	`orSome(F0<A> a)` Returns the value of this optional value or the given argument.
`static <A> Option<List<A>>`	`sequence(List<Option<A>> a)` Sequence through the option monad.
`<B> Option<B>`	`sequence(Option<B> o)` Performs a bind across the optional value, but ignores the element value in the function.
`static <T> F<T,Option<T>>`	`some_()`
`abstract A`	`some()` Returns the value from this optional value, or fails if there is no value.
`static <T> Option<T>`	`some(T t)` Constructs an optional value that has a value of the given argument.
`static <A> List<A>`	`somes(List<Option<A>> as)` Returns all the values in the given list.
`static <A> Stream<A>`	`somes(Stream<Option<A>> as)` Returns all the values in the given stream.
`Array<A>`	`toArray()` Returns an array projection of this optional value.
`Array<A>`	`toArray(java.lang.Class<A[]> c)` Returns an array projection of this optional value.
`java.util.Collection<A>`	`toCollection()` Projects an immutable collection of this optional value.
`static <A,X> F<Option<A>,F<X,Either<X,A>>>`	`toEither()` A first-class version of the toEither method.
`<X> Either<X,A>`	`toEither(F0<X> x)` Returns an either projection of this optional value; the given argument in `Left` if no value, or the value in `Right`.
`<X> Either<X,A>`	`toEither(X x)` Returns an either projection of this optional value; the given argument in `Left` if no value, or the value in `Right`.
`List<A>`	`toList()` Returns a list projection of this optional value.
`A`	`toNull()` Returns the value from this optional value, or if there is no value, returns `null`.
`Stream<A>`	`toStream()` Returns a stream projection of this optional value.
`java.lang.String`	`toString()`
`<X> Validation<X,A>`	`toValidation(X x)`
`<L,B> Either<L,Option<B>>`	`traverseEither(F<A,Either<L,B>> f)`
`<B> IO<Option<B>>`	`traverseIO(F<A,IO<B>> f)`
`<B> List<Option<B>>`	`traverseList(F<A,List<B>> f)`
`<B> Option<Option<B>>`	`traverseOption(F<A,Option<B>> f)`
`<B> P1<Option<B>>`	`traverseP1(F<A,P1<B>> f)`
`<B> Seq<Option<B>>`	`traverseSeq(F<A,Seq<B>> f)`
`<B> F2<Ord<B>,F<A,Set<B>>,Set<Option<B>>>`	`traverseSet()`
`<B> Set<Option<B>>`	`traverseSet(Ord<B> ord, F<A,Set<B>> f)`
`<B> Stream<Option<B>>`	`traverseStream(F<A,Stream<B>> f)`
`<E,B> Validation<E,Option<B>>`	`traverseValidation(F<A,Validation<E,B>> f)`
`A`	`valueE(F0<java.lang.String> message)` Returns the value of this optional value or fails with the given message.
`A`	`valueE(java.lang.String message)` Returns the value of this optional value or fails with the given message.

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable
forEach, spliterator

- Field Detail
 - parseByte
```
public static final F<java.lang.String,Option<java.lang.Byte>> parseByte
```
 A function that parses a string to a byte.
 - parseDouble
```
public static final F<java.lang.String,Option<java.lang.Double>> parseDouble
```
 A function that parses a string to a double.
 - parseFloat
```
public static final F<java.lang.String,Option<java.lang.Float>> parseFloat
```
 A function that parses a string to a float.
 - parseInt
```
public static final F<java.lang.String,Option<java.lang.Integer>> parseInt
```
 A function that parses a string to an integer.
 - parseLong
```
public static final F<java.lang.String,Option<java.lang.Long>> parseLong
```
 A function that parses a string to a long.
 - parseShort
```
public static final F<java.lang.String,Option<java.lang.Short>> parseShort
```
 A function that parses a string to a short.
- Method Detail
 - toString
```
public final java.lang.String toString()
```
 Overrides:
 
 toString in class java.lang.Object
 - iterator
```
public final java.util.Iterator<A> iterator()
```
 Returns an iterator for this optional value. This method exists to permit the use in a for-each loop.
 
 Specified by:
 
 iterator in interface java.lang.Iterable<A>
 
 Returns:
 
 A iterator for this optional value.
 - some
```
public abstract A some()
```
 Returns the value from this optional value, or fails if there is no value.
 
 Returns:
 
 The value from this optional value, or fails if there is no value.
 - isSome
```
public final boolean isSome()
```
 Returns true if this optional value has a value, false otherwise.
 
 Returns:
 
 true if this optional value has a value, false otherwise.
 - isNone
```
public final boolean isNone()
```
 Returns false if this optional value has a value, true otherwise.
 
 Returns:
 
 false if this optional value has a value, true otherwise.
 - isSome_
```
public static <A> F<Option<A>,java.lang.Boolean> isSome_()
```
 A first-class version of the isSome method.
 
 Returns:
 
 A function that returns true if a given optional value has a value, otherwise false.
 - isNone_
```
public static <A> F<Option<A>,java.lang.Boolean> isNone_()
```
 A first-class version of the isNone method.
 
 Returns:
 
 A function that returns false if a given optional value has a value, otherwise true.
 - option
```
public final  B option(B b,
 F<A,B> f)
```
 Performs a reduction on this optional value using the given arguments.
 
 Parameters:
 
 b - The value to return if this optional value has no value.
 
 f - The function to apply to the value of this optional value.
 
 Returns:
 
 A reduction on this optional value.
 - option
```
public final  B option(F0 b,
 F<A,B> f)
```
 Performs a reduction on this optional value using the given arguments.
 
 Parameters:
 
 b - The value to return if this optional value has no value.
 
 f - The function to apply to the value of this optional value.
 
 Returns:
 
 A reduction on this optional value.
 - length
```
public final int length()
```
 Returns the length of this optional value; 1 if there is a value, 0 otherwise.
 
 Returns:
 
 The length of this optional value; 1 if there is a value, 0 otherwise.
 - orSome
```
public final A orSome(F0<A> a)
```
 Returns the value of this optional value or the given argument.
 
 Parameters:
 
 a - The argument to return if this optiona value has no value.
 
 Returns:
 
 The value of this optional value or the given argument.
 - orSome
```
public final A orSome(A a)
```
 Returns the value of this optional value or the given argument.
 
 Parameters:
 
 a - The argument to return if this optiona value has no value.
 
 Returns:
 
 The value of this optional value or the given argument.
 - valueE
```
public final A valueE(F0<java.lang.String> message)
```
 Returns the value of this optional value or fails with the given message.
 
 Parameters:
 
 message - The message to fail with if this optional value has no value.
 
 Returns:
 
 The value of this optional value if there there is one.
 - valueE
```
public final A valueE(java.lang.String message)
```
 Returns the value of this optional value or fails with the given message.
 
 Parameters:
 
 message - The message to fail with if this optional value has no value.
 
 Returns:
 
 The value of this optional value if there there is one.
 - map
```
public final  Option map(F<A,B> f)
```
 Maps the given function across this optional value.
 
 Parameters:
 
 f - The function to map across this optional value.
 
 Returns:
 
 A new optional value after the given function has been applied to its element.
 - map
```
public static <A,B> F<F<A,B>,F<Option<A>,Option>> map()
```
 A first-class map function.
 
 Returns:
 
 A function that maps a given function across a given optional value.
 - foreach
```
public final Unit foreach(F<A,Unit> f)
```
 Performs a side-effect for the value of this optional value.
 
 Parameters:
 
 f - The side-effect to perform for the given element.
 
 Returns:
 
 The unit value.
 - foreachDoEffect
```
public final void foreachDoEffect(Effect1<A> f)
```
 Performs a side-effect for the value of this optional value.
 
 Parameters:
 
 f - The side-effect to perform for the given element.
 - filter
```
public final Option<A> filter(F<A,java.lang.Boolean> f)
```
 Filters elements from this optional value by returning only elements which produce true when the given function is applied to them.
 
 Parameters:
 
 f - The predicate function to filter on.
 
 Returns:
 
 A new optional value whose value matches the given predicate if it has one.
 - bind
```
public final  Option bind(F<A,Option> f)
```
 Binds the given function across the element of this optional value with a final join.
 
 Parameters:
 
 f - The function to apply to the element of this optional value.
 
 Returns:
 
 A new optional value after performing the map, then final join.
 - bind
```
public final <B,C> Option<C> bind(Option ob,
 F<A,F<B,C>> f)
```
 Binds the given function across the element of this optional value and the given optional value with a final join.
 
 Parameters:
 
 ob - A given optional value to bind the given function with.
 
 f - The function to apply to the element of this optional value and the given optional value.
 
 Returns:
 
 A new optional value after performing the map, then final join.
 - bind
```
public final <B,C,D> Option<D> bind(Option ob,
 Option<C> oc,
 F<A,F<B,F<C,D>>> f)
```
 Binds the given function across the element of this optional value and the given optional value with a final join.
 
 Parameters:
 
 ob - A given optional value to bind the given function with.
 
 oc - A given optional value to bind the given function with.
 
 f - The function to apply to the element of this optional value and the given optional value.
 
 Returns:
 
 A new optional value after performing the map, then final join.
 - bind
```
public final <B,C,D,E> Option<E> bind(Option ob,
 Option<C> oc,
 Option<D> od,
 F<A,F<B,F<C,F<D,E>>>> f)
```
 Binds the given function across the element of this optional value and the given optional value with a final join.
 
 Parameters:
 
 ob - A given optional value to bind the given function with.
 
 oc - A given optional value to bind the given function with.
 
 od - A given optional value to bind the given function with.
 
 f - The function to apply to the element of this optional value and the given optional value.
 
 Returns:
 
 A new optional value after performing the map, then final join.
 - bind
```
public final <B,C,D,E,F$> Option<F$> bind(Option ob,
 Option<C> oc,
 Option<D> od,
 Option<E> oe,
 F<A,F<B,F<C,F<D,F<E,F$>>>>> f)
```
 Binds the given function across the element of this optional value and the given optional value with a final join.
 
 Parameters:
 
 ob - A given optional value to bind the given function with.
 
 oc - A given optional value to bind the given function with.
 
 od - A given optional value to bind the given function with.
 
 oe - A given optional value to bind the given function with.
 
 f - The function to apply to the element of this optional value and the given optional value.
 
 Returns:
 
 A new optional value after performing the map, then final join.
 - bind
```
public final <B,C,D,E,F$,G> Option<G> bind(Option ob,
 Option<C> oc,
 Option<D> od,
 Option<E> oe,
 Option<F$> of,
 F<A,F<B,F<C,F<D,F<E,F<F$,G>>>>>> f)
```
 Binds the given function across the element of this optional value and the given optional value with a final join.
 
 Parameters:
 
 ob - A given optional value to bind the given function with.
 
 oc - A given optional value to bind the given function with.
 
 od - A given optional value to bind the given function with.
 
 oe - A given optional value to bind the given function with.
 
 of - A given optional value to bind the given function with.
 
 f - The function to apply to the element of this optional value and the given optional value.
 
 Returns:
 
 A new optional value after performing the map, then final join.
 - bind
```
public final <B,C,D,E,F$,G,H> Option<H> bind(Option ob,
 Option<C> oc,
 Option<D> od,
 Option<E> oe,
 Option<F$> of,
 Option<G> og,
 F<A,F<B,F<C,F<D,F<E,F<F$,F<G,H>>>>>>> f)
```
 Binds the given function across the element of this optional value and the given optional value with a final join.
 
 Parameters:
 
 ob - A given optional value to bind the given function with.
 
 oc - A given optional value to bind the given function with.
 
 od - A given optional value to bind the given function with.
 
 oe - A given optional value to bind the given function with.
 
 of - A given optional value to bind the given function with.
 
 og - A given optional value to bind the given function with.
 
 f - The function to apply to the element of this optional value and the given optional value.
 
 Returns:
 
 A new optional value after performing the map, then final join.
 - bind
```
public final <B,C,D,E,F$,G,H,I> Option bind(Option ob,
 Option<C> oc,
 Option<D> od,
 Option<E> oe,
 Option<F$> of,
 Option<G> og,
 Option<H> oh,
 F<A,F<B,F<C,F<D,F<E,F<F$,F<G,F<H,I>>>>>>>> f)
```
 Binds the given function across the element of this optional value and the given optional value with a final join.
 
 Parameters:
 
 ob - A given optional value to bind the given function with.
 
 oc - A given optional value to bind the given function with.
 
 od - A given optional value to bind the given function with.
 
 oe - A given optional value to bind the given function with.
 
 of - A given optional value to bind the given function with.
 
 og - A given optional value to bind the given function with.
 
 oh - A given optional value to bind the given function with.
 
 f - The function to apply to the element of this optional value and the given optional value.
 
 Returns:
 
 A new optional value after performing the map, then final join.
 - bindProduct
```
public final  Option<P2<A,B>> bindProduct(Option ob)
```
 - bindProduct
```
public final <B,C> Option<P3<A,B,C>> bindProduct(Option ob,
 Option<C> oc)
```
 - bindProduct
```
public final <B,C,D> Option<P4<A,B,C,D>> bindProduct(Option ob,
 Option<C> oc,
 Option<D> od)
```
 - bindProduct
```
public final <B,C,D,E> Option<P5<A,B,C,D,E>> bindProduct(Option ob,
 Option<C> oc,
 Option<D> od,
 Option<E> oe)
```
 - bindProduct
```
public final <B,C,D,E,F$> Option<P6<A,B,C,D,E,F$>> bindProduct(Option ob,
 Option<C> oc,
 Option<D> od,
 Option<E> oe,
 Option<F$> of)
```
 - bindProduct
```
public final <B,C,D,E,F$,G> Option<P7<A,B,C,D,E,F$,G>> bindProduct(Option ob,
 Option<C> oc,
 Option<D> od,
 Option<E> oe,
 Option<F$> of,
 Option<G> og)
```
 - bindProduct
```
public final <B,C,D,E,F$,G,H> Option<P8<A,B,C,D,E,F$,G,H>> bindProduct(Option ob,
 Option<C> oc,
 Option<D> od,
 Option<E> oe,
 Option<F$> of,
 Option<G> og,
 Option<H> oh)
```
 - sequence
```
public final  Option sequence(Option o)
```
 Performs a bind across the optional value, but ignores the element value in the function.
 
 Parameters:
 
 o - The optional value to apply in the final join.
 
 Returns:
 
 A new optional value after the final join.
 - traverseEither
```
public final <L,B> Either<L,Option> traverseEither(F<A,Either<L,B>> f)
```
 - traverseIO
```
public final  IO<Option> traverseIO(F<A,IO> f)
```
 - traverseList
```
public final  List<Option> traverseList(F<A,List> f)
```
 - traverseOption
```
public final  Option<Option> traverseOption(F<A,Option> f)
```
 - traverseStream
```
public final  Stream<Option> traverseStream(F<A,Stream> f)
```
 - traverseP1
```
public final  P1<Option> traverseP1(F<A,P1> f)
```
 - traverseSeq
```
public final  Seq<Option> traverseSeq(F<A,Seq> f)
```
 - traverseSet
```
public final  Set<Option> traverseSet(Ord ord,
 F<A,Set> f)
```
 - traverseSet
```
public final  F2<Ord,F<A,Set>,Set<Option>> traverseSet()
```
 - traverseValidation
```
public final <E,B> Validation<E,Option> traverseValidation(F<A,Validation<E,B>> f)
```
 - apply
```
public final  Option apply(Option<F<A,B>> of)
```
 Performs function application within an optional value (applicative functor pattern).
 
 Parameters:
 
 of - The optional value of functions to apply.
 
 Returns:
 
 A new optional value after applying the given optional value of functions through this optional value.
 - orElse
```
public final Option<A> orElse(F0<Option<A>> o)
```
 Returns this optional value if there is one, otherwise, returns the argument optional value.
 
 Parameters:
 
 o - The optional value to return if this optional value has no value.
 
 Returns:
 
 This optional value if there is one, otherwise, returns the argument optional value.
 - orElse
```
public final Option<A> orElse(Option<A> o)
```
 Returns this optional value if there is one, otherwise, returns the argument optional value.
 
 Parameters:
 
 o - The optional value to return if this optional value has no value.
 
 Returns:
 
 This optional value if there is one, otherwise, returns the argument optional value.
 - toEither
```
public final <X> Either<X,A> toEither(F0<X> x)
```
 Returns an either projection of this optional value; the given argument in Left if no value, or the value in Right.
 
 Parameters:
 
 x - The value to return in left if this optional value has no value.
 
 Returns:
 
 An either projection of this optional value.
 - toEither
```
public final <X> Either<X,A> toEither(X x)
```
 Returns an either projection of this optional value; the given argument in Left if no value, or the value in Right.
 
 Parameters:
 
 x - The value to return in left if this optional value has no value.
 
 Returns:
 
 An either projection of this optional value.
 - toValidation
```
public final <X> Validation<X,A> toValidation(X x)
```
 - toEither
```
public static <A,X> F<Option<A>,F<X,Either<X,A>>> toEither()
```
 A first-class version of the toEither method.
 
 Returns:
 
 A function that returns an either projection of a given optional value, given a value to return in left.
 - toList
```
public final List<A> toList()
```
 Returns a list projection of this optional value.
 
 Returns:
 
 A list projection of this optional value.
 - toStream
```
public final Stream<A> toStream()
```
 Returns a stream projection of this optional value.
 
 Returns:
 
 A stream projection of this optional value.
 - toArray
```
public final Array<A> toArray()
```
 Returns an array projection of this optional value.
 
 Returns:
 
 An array projection of this optional value.
 - toArray
```
public final Array<A> toArray(java.lang.Class<A[]> c)
```
 Returns an array projection of this optional value.
 
 Parameters:
 
 c - The class type of the array to return.
 
 Returns:
 
 An array projection of this optional value.
 - array
```
public final A[] array(java.lang.Class<A[]> c)
```
 Returns an array from this optional value.
 
 Parameters:
 
 c - The class type of the array to return.
 
 Returns:
 
 An array from this optional value.
 - toNull
```
public final A toNull()
```
 Returns the value from this optional value, or if there is no value, returns null. This is intended for interfacing with APIs that expect a null for non-existence.
 
 Returns:
 
 This optional value or null if there is no value.
 - forall
```
public final boolean forall(F<A,java.lang.Boolean> f)
```
 Returns true if this optional value has no value, or the predicate holds for the given predicate function, false otherwise.
 
 Parameters:
 
 f - the predicate function to test on the value of this optional value.
 
 Returns:
 
 true if this optional value has no value, or the predicate holds for the given predicate function, false otherwise.
 - exists
```
public final boolean exists(F<A,java.lang.Boolean> f)
```
 Returns true is this optional value has a value and the given predicate function holds on that value, false otherwise.
 
 Parameters:
 
 f - the predicate function to test on the value of this optional value.
 
 Returns:
 
 true is this optional value has a value and the given predicate function holds on that value, false otherwise.
 - equals
```
public final boolean equals(java.lang.Object other)
```
 Overrides:
 
 equals in class java.lang.Object
 - toCollection
```
public final java.util.Collection<A> toCollection()
```
 Projects an immutable collection of this optional value.
 
 Returns:
 
 An immutable collection of this optional value.
 - some_
```
public static <T> F<T,Option<T>> some_()
```
 - some
```
public static <T> Option<T> some(T t)
```
 Constructs an optional value that has a value of the given argument.
 
 Parameters:
 
 t - The value for the returned optional value.
 
 Returns:
 
 An optional value that has a value of the given argument.
 - none_
```
public static <T> F<T,Option<T>> none_()
```
 - none
```
public static <T> Option<T> none()
```
 Constructs an optional value that has no value.
 
 Returns:
 
 An optional value that has no value.
 - fromNull
```
public static <T> Option<T> fromNull(T t)
```
 Turns an unsafe nullable value into a safe optional value. If t == null then return none, otherwise, return the given value in some.
 
 Parameters:
 
 t - The unsafe nullable value.
 
 Returns:
 
 If t == null then return none, otherwise, return it in some.
 - fromNull
```
public static <T> F<T,Option<T>> fromNull()
```
 Turns an unsafe nullable value into a safe optional value. If t == null then return none, otherwise, return the given value in some.
 
 Returns:
 
 If t == null then return none, otherwise, return it in some.
 - option_
```
public static final <A,B> F<Option<A>,B> option_(B none,
 F<A,B> some)
```
 First-class catamorphism for Option: return a function that will performs a reduction on an optional value using the given arguments.
 
 Parameters:
 
 none - The value to return if this optional value has no value.
 
 some - The function to apply to the value of this optional value.
 
 Returns:
 
 the reducing function.
 - join
```
public static <A> Option<A> join(Option<Option<A>> o)
```
 Joins the given optional value of optional value using a bind operation.
 
 Parameters:
 
 o - The optional value of optional value to join.
 
 Returns:
 
 A new optional value that is the join of the given optional value.
 - sequence
```
public static <A> Option<List<A>> sequence(List<Option<A>> a)
```
 Sequence through the option monad.
 
 Parameters:
 
 a - The list of option to sequence.
 
 Returns:
 
 The option of list after sequencing.
 - iif
```
public static <A> Option<A> iif(F<A,java.lang.Boolean> f,
 A a)
```
 Returns an optional value that has a value of the given argument, if the given predicate holds on that argument, otherwise, returns no value.
 
 Parameters:
 
 f - The predicate to test on the given argument.
 
 a - The argument to test the predicate on and potentially use as the value of the returned optional value.
 
 Returns:
 
 an optional value that has a value of the given argument, if the given predicate holds on that argument, otherwise, returns no value.
 - iif
```
public static <A> Option<A> iif(boolean p,
 F0<A> a)
```
 Returns an optional value that has a value of the given argument if the given boolean is true, otherwise, returns no value.
 
 Parameters:
 
 p - The value to be true to return the given value.
 
 a - the value to return in an optional value if the given boolean is true.
 
 Returns:
 
 An optional value that has a value of the given argument if the given boolean is true, otherwise, returns no value.
 - iif
```
public static <A> Option<A> iif(boolean p,
 A a)
```
 Returns an optional value that has a value of the given argument if the given boolean is true, otherwise, returns no value.
 
 Parameters:
 
 p - The value to be true to return the given value.
 
 a - the value to return in an optional value if the given boolean is true.
 
 Returns:
 
 An optional value that has a value of the given argument if the given boolean is true, otherwise, returns no value.
 - iif
```
public static <A> F2<F<A,java.lang.Boolean>,A,Option<A>> iif()
```
 First-class version of the iif function.
 
 Returns:
 
 a function that returns an optional value that has a value of the given argument, if the given predicate holds on that argument, or no value otherwise.
 - somes
```
public static <A> List<A> somes(List<Option<A>> as)
```
 Returns all the values in the given list.
 
 Parameters:
 
 as - The list of potential values to get actual values from.
 
 Returns:
 
 All the values in the given list.
 - somes
```
public static <A> Stream<A> somes(Stream<Option<A>> as)
```
 Returns all the values in the given stream.
 
 Parameters:
 
 as - The stream of potential values to get actual values from.
 
 Returns:
 
 All the values in the given stream.
 - fromString
```
public static Option<java.lang.String> fromString(java.lang.String s)
```
 Returns an optional non-empty string, or no value if the given string is empty.
 
 Parameters:
 
 s - A string to turn into an optional non-empty string.
 
 Returns:
 
 an optional non-empty string, or no value if the given string is empty.
 - hashCode
```
public final int hashCode()
```
 Overrides:
 
 hashCode in class java.lang.Object
 - fromString
```
public static F<java.lang.String,Option<java.lang.String>> fromString()
```
 Returns a function that transforms a string to an optional non-empty string, or no value if the string is empty.
 
 Returns:
 
 a function that transforms a string to an optional non-empty string, or no value if the string is empty.
 - fromSome
```
public static <A> F<Option<A>,A> fromSome()
```
 Returns a function that takes an optional value to a value or errors if there is no value.
 
 Returns:
 
 A function that takes an optional value to a value or errors if there is no value.
 - liftM2
```
public static <A,B,C> F<Option<A>,F<Option,Option<C>>> liftM2(F<A,F<B,C>> f)
```
 Promotes a function of arity-2 so that it operates over options.
 
 Parameters:
 
 f - A function to promote.
 
 Returns:
 
 The given function promoted to operate on options.
 - liftM2
```
public final <B,C> Option<C> liftM2(Option ob,
 F2<A,B,C> f)
```
 Lift the function of arity-2 through options.
 
 Parameters:
 
 f - A function to lift.
 
 Returns:
 
 An optional result.
 - bind
```
public static <A,B> F<F<A,Option>,F<Option<A>,Option>> bind()
```
 First-class bind function.
 
 Returns:
 
 A function that binds a given function across an option with a final join.
 - join
```
public static <A> F<Option<Option<A>>,Option<A>> join()
```
 First-class join function.
 
 Returns:
 
 A function that joins an Option of an Option to make a single Option.

Class Option<A>

Nested Class Summary

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.lang.Iterable

Field Detail

parseByte

parseDouble

parseFloat

parseInt

parseLong

parseShort

Method Detail

toString

iterator

some

isSome

isNone

isSome_

isNone_

option

option

length

orSome

orSome

valueE

valueE

map

map

foreach

foreachDoEffect

filter

bind

bind

bind

bind

bind

bind

bind

bind

bindProduct

bindProduct

bindProduct

bindProduct

bindProduct

bindProduct

bindProduct

sequence

traverseEither

traverseIO

traverseList

traverseOption

traverseStream

traverseP1

traverseSeq

traverseSet

traverseSet

traverseValidation

apply

orElse

orElse

toEither

toEither

toValidation

toEither

toList

toStream

toArray

toArray

array

toNull

forall

exists

equals

toCollection

some_

some

none_

none