Class Option<A>

java.lang.Object

fj.data.Option<A>

All Implemented Interfaces:

Iterable<A>

Direct Known Subclasses:

Option.None, Option.Some

public abstract class Option<A>
extends Object
implements 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	Description
private static final class	Option.None<A>
static final class	Option.Optic
private static final class	Option.Some<A>

Field Summary

Fields

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

Constructor Summary

Constructors

Modifier	Constructor	Description
private	Option()

Method Summary

Modifier and Type	Method	Description
final <B> Option<B>	apply(Option<F<A,B>> of)	Performs function application within an optional value (applicative functor pattern).
final A[]	array(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.
final <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$, F<G,F<H,I>>>>>>>> f)	Binds the given function across the element of this optional value and the given optional value with a final join.
final <B,C,D,E,F$,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.
final <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$,G>>>>>> f)	Binds the given function across the element of this optional value and the given optional value with a final join.
final <B,C,D,E,F$> 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.
final <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.
final <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.
final <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.
final <B> Option<B>	bind(F<A, Option<B>> f)	Binds the given function across the element of this optional value with a final join.
final <B> Option<P2<A,B>>	bindProduct(Option<B> ob)
final <B,C> Option<P3<A,B,C>>	bindProduct(Option<B> ob, Option<C> oc)
final <B,C,D> Option<P4<A,B,C,D>>	bindProduct(Option<B> ob, Option<C> oc, Option<D> od)
final <B,C,D,E> Option<P5<A,B,C,D,E>>	bindProduct(Option<B> ob, Option<C> oc, Option<D> od, Option<E> oe)
final <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$> of)
final <B,C,D,E,F$,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)
final <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)
final boolean	equals(Object other)
final boolean	exists(F<A,Boolean> f)	Returns true is this optional value has a value and the given predicate function holds on that value, false otherwise.
final Option<A>	filter(F<A,Boolean> f)	Filters elements from this optional value by returning only elements which produce true when the given function is applied to them.
final boolean	forall(F<A,Boolean> f)	Returns true if this optional value has no value, or the predicate holds for the given predicate function, false otherwise.
final Unit	foreach(F<A,Unit> f)	Performs a side-effect for the value of this optional value.
final 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<String, Option<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<String>	fromString(String s)	Returns an optional non-empty string, or no value if the given string is empty.
final int	hashCode()
static <A> F2<F<A,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,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.
final boolean	isNone()	Returns false if this optional value has a value, true otherwise.
static <A> F<Option<A>, Boolean>	isNone_()	A first-class version of the isNone method.
final boolean	isSome()	Returns true if this optional value has a value, false otherwise.
static <A> F<Option<A>, Boolean>	isSome_()	A first-class version of the isSome method.
final 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.
final int	length()	Returns the length of this optional value; 1 if there is a value, 0 otherwise.
final <B,C> Option<C>	liftM2(Option<B> ob, F2<A,B,C> f)	Lift the function of arity-2 through options.
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.
static <A,B> F<F<A,B>, F<Option<A>, Option<B>>>	map()	A first-class map function.
final <B> Option<B>	map(F<A,B> f)	Maps the given function across this optional value.
static <T> Option<T>	none()	Constructs an optional value that has no value.
static <T> F<T, Option<T>>	none_()
final <B> B	option(B b, F<A,B> f)	Performs a reduction on this optional value using the given arguments.
final <B> B	option(F0<B> b, F<A,B> f)	Performs a reduction on this optional value using the given arguments.
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.
final Option<A>	orElse(Option<A> o)	Returns this optional value if there is one, otherwise, returns the argument optional value.
final Option<A>	orElse(F0<Option<A>> o)	Returns this optional value if there is one, otherwise, returns the argument optional value.
final A	orSome(A a)	Returns the value of this optional value or the given argument.
final 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 a list through the option monad.
final <B> Option<B>	sequence(Option<B> o)	Performs a bind across the optional value, but ignores the element value in the function.
static <E,A> Option<Validation<E,A>>	sequence(Validation<E, Option<A>> a)	Sequence a validation through the option monad.
static final <L,B> Either<L, Option<B>>	sequenceEither(Option<Either<L,B>> option)	Sequence the given option and collect the output on the right side of an either.
static final <R,B> Either<Option<B>, R>	sequenceEitherLeft(Option<Either<B,R>> option)	Sequence the given option and collect the output on the left side of an either.
static final <L,B> Either<L, Option<B>>	sequenceEitherRight(Option<Either<L,B>> option)	Sequence the given option and collect the output on the right side of an either.
static final <C,B> F<C, Option<B>>	sequenceF(Option<F<C,B>> option)	Sequence the given option and collect the output as a function.
static final <B> IO<Option<B>>	sequenceIO(Option<IO<B>> option)	Sequence the given option and collect the output as an IO.
static final <B> List<Option<B>>	sequenceList(Option<List<B>> option)	Sequence the given option and collect the output as an list.
static final <B> Option<Option<B>>	sequenceOption(Option<Option<B>> option)	Sequence the given option and collect the output as an option.
static final <B> P1<Option<B>>	sequenceP1(Option<P1<B>> option)	Sequence the given option and collect the output as a P1.
static final <B> Seq<Option<B>>	sequenceSeq(Option<Seq<B>> option)	Sequence the given option and collect the output as a seq.
static final <B> Set<Option<B>>	sequenceSet(Ord<B> ord, Option<Set<B>> option)	Sequence the given option and collect the output as a set; use the given ord to order the set.
static final <B> Stream<Option<B>>	sequenceStream(Option<Stream<B>> option)	Sequence the given option and collect the output as a stream.
static final <B> Trampoline<Option<B>>	sequenceTrampoline(Option<Trampoline<B>> option)	Sequence the given option and collect the output as a trampoline.
static final <E,B> Validation<E, Option<B>>	sequenceValidation(Option<Validation<E,B>> option)	Sequence the given option and collect the output as a validation.
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 <T> F<T, Option<T>>	some_()
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.
final Array<A>	toArray()	Returns an array projection of this optional value.
final Array<A>	toArray(Class<A[]> c)	Returns an array projection of this optional value.
final 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.
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.
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.
final List<A>	toList()	Returns a list projection of this optional value.
final A	toNull()	Returns the value from this optional value, or if there is no value, returns null.
final Stream<A>	toStream()	Returns a stream projection of this optional value.
final String	toString()
final <X> Validation<X,A>	toValidation(X x)
final <L,B> Either<L, Option<B>>	traverseEither(F<A, Either<L,B>> f)	Traverse this option with the given function and collect the output on the right side of an either.
final <R,B> Either<Option<B>, R>	traverseEitherLeft(F<A, Either<B,R>> f)	Traverse this option with the given function and collect the output on the left side of an either.
final <L,B> Either<L, Option<B>>	traverseEitherRight(F<A, Either<L,B>> f)	Traverse this option with the given function and collect the output on the right side of an either.
final <C,B> F<C, Option<B>>	traverseF(F<A,F<C,B>> f)	Traverse this option with the given function and collect the output as a function.
final <B> IO<Option<B>>	traverseIO(F<A,IO<B>> f)	Traverse this option with the given function and collect the output as an IO.
final <B> List<Option<B>>	traverseList(F<A,List<B>> f)	Traverse this option with the given function and collect the output as a list.
final <B> Option<Option<B>>	traverseOption(F<A, Option<B>> f)	Traverse this option with the given function and collect the output as an option.
final <B> P1<Option<B>>	traverseP1(F<A,P1<B>> f)	Traverse this option with the given function and collect the output as a P1.
final <B> Seq<Option<B>>	traverseSeq(F<A,Seq<B>> f)	Traverse this option with the given function and collect the output a seq.
final <B> F2<Ord<B>, F<A,Set<B>>, Set<Option<B>>>	traverseSet()
final <B> Set<Option<B>>	traverseSet(Ord<B> ord, F<A,Set<B>> f)	Traverse this option with the given function and collect the output as a set; use the given ord to order the set.
final <B> Stream<Option<B>>	traverseStream(F<A, Stream<B>> f)	Traverse this option with the given function and collect the output as a stream.
final <B> Trampoline<Option<B>>	traverseTrampoline(F<A, Trampoline<B>> f)	Traverse this option with the given function and collect the output as a trampoline.
final <E,B> Validation<E, Option<B>>	traverseValidation(F<A, Validation<E,B>> f)	Traverse this option with the given function and collect the output as a validation.
final A	valueE(F0<String> message)	Returns the value of this optional value or fails with the given message.
final A	valueE(String message)	Returns the value of this optional value or fails with the given message.

Methods inherited from class Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface Iterable

forEach, spliterator

Field Details

parseByte

public static final F<String, Option<Byte>> parseByte

A function that parses a string to a byte.

parseDouble

public static final F<String, Option<Double>> parseDouble

A function that parses a string to a double.

parseFloat

public static final F<String, Option<Float>> parseFloat

A function that parses a string to a float.

parseInt

public static final F<String, Option<Integer>> parseInt

A function that parses a string to an integer.

parseLong

public static final F<String, Option<Long>> parseLong

A function that parses a string to a long.

parseShort

public static final F<String, Option<Short>> parseShort

A function that parses a string to a short.

Constructor Details

Option

private Option()

Method Details

toString

public final String toString()

Overrides:

toString in class Object

iterator

public final 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 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>, 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>, 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> 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> B option(F0<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.

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<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(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 <B> Option<B> 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<B>>> 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,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 <B> Option<B> bind(F<A, Option<B>> 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<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.

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<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.

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<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.

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<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.

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$,G> Option<G> bind(Option<B> ob,
 Option<C> oc,
 Option<D> od,
 Option<E> oe,
 Option<F$> 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.

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$,G,H> Option<H> bind(Option<B> ob,
 Option<C> oc,
 Option<D> od,
 Option<E> oe,
 Option<F$> 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.

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$,G,H,I> Option<I> bind(Option<B> ob,
 Option<C> oc,
 Option<D> od,
 Option<E> oe,
 Option<F$> 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.

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 <B> Option<P2<A,B>> bindProduct(Option<B> ob)

bindProduct

public final <B,C> Option<P3<A,B,C>> bindProduct(Option<B> ob,
 Option<C> oc)

bindProduct

public final <B,C,D> Option<P4<A,B,C,D>> bindProduct(Option<B> ob,
 Option<C> oc,
 Option<D> od)

bindProduct

public final <B,C,D,E> Option<P5<A,B,C,D,E>> bindProduct(Option<B> 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<B> 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<B> 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<B> ob,
 Option<C> oc,
 Option<D> od,
 Option<E> oe,
 Option<F$> of,
 Option<G> og,
 Option<H> oh)

sequence

public final <B> Option<B> sequence(Option<B> 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.

sequenceEither

public static final <L,B> Either<L, Option<B>> sequenceEither(Option<Either<L,B>> option)

Sequence the given option and collect the output on the right side of an either.

Type Parameters:

L - the type of the left value

B - the type of the right value

Parameters:

option - the given option

Returns:

the either

sequenceEitherLeft

public static final <R,B> Either<Option<B>, R> sequenceEitherLeft(Option<Either<B,R>> option)

Sequence the given option and collect the output on the left side of an either.

Type Parameters:

R - the type of the right value

B - the type of the left value

Parameters:

option - the given option

Returns:

the either

sequenceEitherRight

public static final <L,B> Either<L, Option<B>> sequenceEitherRight(Option<Either<L,B>> option)

Sequence the given option and collect the output on the right side of an either.

Type Parameters:

L - the type of the left value

B - the type of the right value

Parameters:

option - the given option

Returns:

the either

sequenceF

public static final <C,B> F<C, Option<B>> sequenceF(Option<F<C,B>> option)

Sequence the given option and collect the output as a function.

Type Parameters:

C - the type of the input value

B - the type of the output value

Parameters:

option - the given option

Returns:

the either

sequenceIO

public static final <B> IO<Option<B>> sequenceIO(Option<IO<B>> option)

Sequence the given option and collect the output as an IO.

Type Parameters:

B - the type of the IO value

Parameters:

option - the given option

Returns:

the IO

sequenceList

public static final <B> List<Option<B>> sequenceList(Option<List<B>> option)

Sequence the given option and collect the output as an list.

Type Parameters:

B - the type of the list value

Parameters:

option - the given option

Returns:

the list

sequenceOption

public static final <B> Option<Option<B>> sequenceOption(Option<Option<B>> option)

Sequence the given option and collect the output as an option.

Type Parameters:

B - the type of the option value

Parameters:

option - the given option

Returns:

the option

sequenceP1

public static final <B> P1<Option<B>> sequenceP1(Option<P1<B>> option)

Sequence the given option and collect the output as a P1.

Type Parameters:

B - the type of the P1 value

Parameters:

option - the given option

Returns:

the P1

sequenceSeq

public static final <B> Seq<Option<B>> sequenceSeq(Option<Seq<B>> option)

Sequence the given option and collect the output as a seq.

Type Parameters:

B - the type of the seq value

Parameters:

option - the given option

Returns:

the seq

sequenceSet

public static final <B> Set<Option<B>> sequenceSet(Ord<B> ord,
 Option<Set<B>> option)

Sequence the given option and collect the output as a set; use the given ord to order the set.

Type Parameters:

B - the type of the set value

Parameters:

ord - the given ord

option - the given option

Returns:

the either

sequenceStream

public static final <B> Stream<Option<B>> sequenceStream(Option<Stream<B>> option)

Sequence the given option and collect the output as a stream.

Type Parameters:

B - the type of the stream value

Parameters:

option - the given option

Returns:

the stream

sequenceTrampoline

public static final <B> Trampoline<Option<B>> sequenceTrampoline(Option<Trampoline<B>> option)

Sequence the given option and collect the output as a trampoline.

Type Parameters:

B - the type of the stream value

Parameters:

option - the given trampoline

Returns:

the stream

sequenceValidation

public static final <E,B> Validation<E, Option<B>> sequenceValidation(Option<Validation<E,B>> option)

Sequence the given option and collect the output as a validation.

Type Parameters:

E - the type of the failure value

B - the type of the success value

Parameters:

option - the given option

Returns:

the validation

traverseEither

public final <L,B> Either<L, Option<B>> traverseEither(F<A, Either<L,B>> f)

Traverse this option with the given function and collect the output on the right side of an either.

Type Parameters:

L - the type of the left value

B - the type of the right value

Parameters:

f - the given function

Returns:

the either

traverseEitherLeft

public final <R,B> Either<Option<B>, R> traverseEitherLeft(F<A, Either<B,R>> f)

Traverse this option with the given function and collect the output on the left side of an either.

Type Parameters:

R - the type of the left value

B - the type of the right value

Parameters:

f - the given function

Returns:

the either

traverseEitherRight

public final <L,B> Either<L, Option<B>> traverseEitherRight(F<A, Either<L,B>> f)

Traverse this option with the given function and collect the output on the right side of an either.

Type Parameters:

L - the type of the left value

B - the type of the right value

Parameters:

f - the given function

Returns:

the either

traverseF

public final <C,B> F<C, Option<B>> traverseF(F<A,F<C,B>> f)

Traverse this option with the given function and collect the output as a function.

Type Parameters:

C - the type of the input value

B - the type of the output value

Parameters:

f - the given function

Returns:

the function

traverseIO

public final <B> IO<Option<B>> traverseIO(F<A,IO<B>> f)

Traverse this option with the given function and collect the output as an IO.

Type Parameters:

B - the type of the IO value

Parameters:

f - the given function

Returns:

the IO

traverseList

public final <B> List<Option<B>> traverseList(F<A,List<B>> f)

Traverse this option with the given function and collect the output as a list.

Type Parameters:

B - the type of the list value

Parameters:

f - the given function

Returns:

the list

traverseOption

public final <B> Option<Option<B>> traverseOption(F<A, Option<B>> f)

Traverse this option with the given function and collect the output as an option.

Type Parameters:

B - the type of the option value

Parameters:

f - the given function

Returns:

the option

traverseP1

public final <B> P1<Option<B>> traverseP1(F<A,P1<B>> f)

Traverse this option with the given function and collect the output as a P1.

Type Parameters:

B - the type of the P1 value

Parameters:

f - the given function

Returns:

the P1

traverseSeq

public final <B> Seq<Option<B>> traverseSeq(F<A,Seq<B>> f)

Traverse this option with the given function and collect the output a seq.

Type Parameters:

B - the type of the seq value

Parameters:

f - the given function

Returns:

the seq

traverseSet

public final <B> Set<Option<B>> traverseSet(Ord<B> ord,
 F<A,Set<B>> f)

Traverse this option with the given function and collect the output as a set; use the given ord to order the set.

Type Parameters:

B - the type of the set value

Parameters:

ord - the given ord

f - the given function

Returns:

the set

traverseStream

public final <B> Stream<Option<B>> traverseStream(F<A, Stream<B>> f)

Traverse this option with the given function and collect the output as a stream.

Type Parameters:

B - the type of the stream value

Parameters:

f - the given function

Returns:

the stream

traverseTrampoline

public final <B> Trampoline<Option<B>> traverseTrampoline(F<A, Trampoline<B>> f)

Traverse this option with the given function and collect the output as a trampoline.

Type Parameters:

B - the type of the trampoline value

Parameters:

f - the given function

Returns:

the trampoline

traverseValidation

public final <E,B> Validation<E, Option<B>> traverseValidation(F<A, Validation<E,B>> f)

Traverse this option with the given function and collect the output as a validation.

Type Parameters:

E - the type of the failure value

B - the type of the success value

Parameters:

f - the given function

Returns:

the validation

traverseSet

public final <B>
F2<Ord<B>, F<A,Set<B>>, Set<Option<B>>> traverseSet()

apply

public final <B> Option<B> 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(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(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,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,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(Object other)

Overrides:

equals in class Object

toCollection

public final 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 a list through the option monad.

Parameters:

a - The list of option to sequence.

Returns:

The option of list after sequencing.

sequence

public static <E,A> Option<Validation<E,A>> sequence(Validation<E, Option<A>> a)

Sequence a validation through the option monad.

Parameters:

a - The validation of option to sequence.

Returns:

The option of validation after sequencing.

iif

public static <A> Option<A> iif(F<A,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,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<String> fromString(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 Object

fromString

public static F<String, Option<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<B>, 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<B> 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<B>>, F<Option<A>, Option<B>>> 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.