Option

Small package that brings DOP of Optional to Java.

Gives you the possibility to write code as

import io.github.ashr123.option.None;
import io.github.ashr123.option.Option;
import io.github.ashr123.option.Some;

public record Pair<L, R>(L left, R right) {
}

public static Integer intABSOption(Integer integer) {
	return switch (Option.of(integer)) {
		case Some(Integer i) when i < 0 -> -i;
		case Some(Integer i) -> i;
		case None<Integer> ignored -> null;
		case None() -> null; // effectively same as the case above
	};
}

public static Integer intMax(Pair<Integer, Integer> pair) {
	return switch (Option.of(pair)) {
		case Some(Pair(Integer l, Integer r)) when l != null && r == null -> l;
		case Some(Pair(Integer l, Integer r)) when l == null && r != null -> r;
		case Some(Pair(Integer l, Integer r)) when l != null && r != null && l > r -> l;
		case Some(Pair(Integer l, Integer r)) -> r;
		case None() -> null;
	};
}

Comparison against existing Optional<T>

Optional methods	Option<T> opt equivalent
empty()	new None<>()
of(T value)	new Some<>(T value)
ofNullable(T value)	of(T value) of(Optional<T> value)
get()	switch-case if (opt instanceof Some(T value)) ...
isPresent()	if (opt instanceof Some<?>) ...
isEmpty()	if (opt instanceof None<?>) ...
ifPresent(Consumer<? super T> action)	switch-case if (opt instanceof Some(T value)) value ...
ifPresentOrElse(Consumer<? super T> action, Runnable emptyAction)	switch-case
filter(Predicate<? super T> predicate)	if (opt instanceof Some(T value) && value ...)
map(Function<? super T, ? extends U> mapper)	if (opt instanceof Some(T value)) value ...
flatMap(Function<? super T, ? extends Optional<? extends U>> mapper)	flatMap(Function<? super T, ? extends Option<? extends U>> mapper)
or(Supplier<? extends Optional<? extends T>> supplier)	switch-case
stream()	stream()
orElse(T other)	switch-case
orElseGet(Supplier<? extends T> supplier)	switch-case
orElseThrow()	switch-case
orElseThrow(Supplier<? extends X> exceptionSupplier)	switch-case

Requires JRE 21 or above.