#22 Added Either Monad

Author: redomar

src/com/redomar/game/lib/Either.java

@@ -0,0 +1,38 @@
+package com.redomar.game.lib;
+
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Optional;
+
+public class Either<L, R> {
+	private final Optional<L> left;
+	private final Optional<R> right;
+
+	private Either(final Optional<L> left, final Optional<R> right) {
+		this.left = left;
+		this.right = right;
+	}
+
+	@Contract("_ -> new")
+	static <L, R> @NotNull Either<L, R> left(final L value) {
+		return new Either<>(Optional.of(value), Optional.empty());
+	}
+
+	@Contract("_ -> new")
+	static <L, R> @NotNull Either<L, R> right(final R value) {
+		return new Either<>(Optional.empty(), Optional.of(value));
+	}
+
+	boolean isLeft() {
+		return left.isPresent();
+	}
+
+	L getLeft() {
+		return left.get();
+	}
+
+	R getRight() {
+		return right.get();
+	}
+}