Can we have Either class in Java languare?

[Brian Goetz]

The motivation for Optional was not so much that we wanted to provide the One Official Maybe Monad for Java (in fact, this was the worst part of doing Optional); it was that the JDK APIs needed a better way to indicate a possibly-empty return value.  Since I think the chance is about zero that JDK APIs will migrate from exceptions to Either, this motivation will not be carrying Either into the JDK any time soon…..  


> On Apr 5, 2019, at 3:03 PM, Владимир Шумихин <androiden3201 at gmail.com> wrote:
> 
> Hello,
> 
> Java 8 has introduced a new class Optional -
> https://docs.oracle.com/javase/8/docs/api/java/util/Optional.html This is
> an incredibly useful tool that allows us to avoid NullPointerException.
> 
> There is another very attractive monad. I'm talking about
> Either monad/class. This tool allows us to explicitly handle errors without
> using checked exceptions.
> 
> There are multiple implementations Either in 3-d party libraries:
> 1) http://www.vavr.io/vavr-docs/#_either
> 2) http://www.functionaljava.org/
> 3)
> https://bitbucket.org/atlassian/fugue/src/b0868a00273f8f2ccf5d1a2610a8a5507ce641c4/fugue/src/main/java/com/atlassian/fugue/Either.java?at=master&fileviewer=file-view-default
> 
> So, there is one problem with 3-d party libraries. We have multiple
> implementations Either in classpath of applications, but we have to convert
> one Either to another one.
> 
> Is there any chance that we will have Either in Java SE?
> 
> Thank you for response.