Module info.jab.util

Package info.jab.util.either

Interface Either<L,R>

Type Parameters:

L - the type of the Left value

R - the type of the Right value

All Known Implementing Classes:

Left, Right

public sealed interface Either<L,R>
permits Left<L,R>, Right<L,R>

A generic sealed interface representing a value of one of two possible types (a disjoint union). Instances of Either are either an instance of Left or Right. Inspired by the implemenation from Either (Scala) and Either (ArrowKt)

Author:

Juan Antonio Breña Moral, ChatGPT-40

Method Summary

Modifier and Type	Method	Description
default Either<L,R>	combine(Either<L,R> other, BiFunction<? super R,? super R,? extends R> combiner)	Combines two Either instances using the given combiner function if both are Right.
static <E, A> Either<E,A>	either(Function<Raise<? super E>,? extends A> block)	Converts a computation that might raise an exception of type `E` into an `Either` value.
default <U> Either<L,U>	flatMap(Function<? super R,? extends Either<L,U>> mapper)	Transforms the value in Right using the given function that returns another Either, if this is a Right.
<T> T	fold(Function<? super L,? extends T> leftMapper, Function<? super R,? extends T> rightMapper)	Applies either the leftMapper function to the value if this is a Left, or the rightMapper function if this is a Right.
R	get()	Returns the value if this is a Right, otherwise throws an exception.
default R	getOrElse(Supplier<? extends R> other)	Returns the Right value if this is a Right, otherwise returns the result of the given Supplier.
boolean	isLeft()	Checks if this is an instance of Left.
boolean	isRight()	Checks if this is an instance of Right.
static <L, R> Either<L,R>	left(L value)	Creates an instance of Left.
default <U> Either<L,U>	map(Function<? super R,? extends U> mapper)	Transforms the value in Right using the given function if this is a Right, otherwise returns the current Left.
default Either<L,R>	orElse(Supplier<? extends Either<L,R>> other)	Returns this Either if it is a Right, otherwise returns the result of the given Supplier.
static <L, R> Either<L,R>	right(R value)	Creates an instance of Right.
default Either<R,L>	swap()	Swaps the Left and Right types.
default Optional<R>	toOptional()	Converts this Either to an Optional.

Method Details

fold

<T> T fold(Function<? super L,? extends T> leftMapper,
 Function<? super R,? extends T> rightMapper)

Applies either the leftMapper function to the value if this is a Left, or the rightMapper function if this is a Right.

Type Parameters:

T - the type of the result

Parameters:

leftMapper - the function to apply if this is a Left

rightMapper - the function to apply if this is a Right

Returns:

the result of applying the appropriate function

isLeft

boolean isLeft()

Checks if this is an instance of Left.

Returns:

true if this is a Left, false otherwise

isRight

boolean isRight()

Checks if this is an instance of Right.

Returns:

true if this is a Right, false otherwise

left

static <L,
R> Either<L,R> left(@Nonnull
 L value)

Creates an instance of Left.

Type Parameters:

L - the type of the Left value

R - the type of the Right value

Parameters:

value - the value to be wrapped in Left

Returns:

a Left containing the given value

right

static <L,
R> Either<L,R> right(@Nonnull
 R value)

Creates an instance of Right.

Type Parameters:

L - the type of the Left value

R - the type of the Right value

Parameters:

value - the value to be wrapped in Right

Returns:

a Right containing the given value

map

default <U> Either<L,U> map(Function<? super R,? extends U> mapper)

Transforms the value in Right using the given function if this is a Right, otherwise returns the current Left.

Type Parameters:

U - the type of the new Right value

Parameters:

mapper - the function to apply to the Right value

Returns:

a new Either instance

flatMap

default <U> Either<L,U> flatMap(Function<? super R,? extends Either<L,U>> mapper)

Transforms the value in Right using the given function that returns another Either, if this is a Right. Otherwise, returns the current Left.

Type Parameters:

U - the type of the new Right value

Parameters:

mapper - the function to apply to the Right value

Returns:

a new Either instance

swap

default Either<R,L> swap()

Swaps the Left and Right types. Converts a Left to a Right and vice versa.

Returns:

a new Either instance with the Left and Right types swapped

getOrElse

default R getOrElse(Supplier<? extends R> other)

Returns the Right value if this is a Right, otherwise returns the result of the given Supplier.

Parameters:

other - a Supplier whose result is returned if this is a Left

Returns:

the Right value or the result of the Supplier

orElse

default Either<L,R> orElse(Supplier<? extends Either<L,R>> other)

Returns this Either if it is a Right, otherwise returns the result of the given Supplier.

Parameters:

other - a Supplier whose result is returned if this is a Left

Returns:

this Either or the result of the Supplier

combine

default Either<L,R> combine(Either<L,R> other,
 BiFunction<? super R,? super R,? extends R> combiner)

Combines two Either instances using the given combiner function if both are Right. Otherwise, returns the first Right instance encountered, or the last Left if both are Left.

Parameters:

other - another Either instance to combine with

combiner - a BiFunction to combine the Right values

Returns:

a new Either instance resulting from the combination

toOptional

default Optional<R> toOptional()

Converts this Either to an Optional. If this is a Right, the Optional will contain the value. If this is a Left, the Optional will be empty.

Returns:

an Optional containing the Right value if present, otherwise an empty Optional

get

R get()

Returns the value if this is a Right, otherwise throws an exception.

Returns:

the Right value

Throws:

NoSuchElementException - if this is a Left

either

static <E,
A> Either<E,A> either(Function<Raise<? super E>,? extends A> block)

Converts a computation that might raise an exception of type `E` into an `Either` value. The computation is represented by a function that takes a Raise object as input.

Type Parameters:

E - The type of the exception that can be raised by the computation.

A - The type of the value returned by the computation if it succeeds.

Parameters:

block - The function that encapsulates the computation.

Returns:

An `Either` value representing the result of the computation.