PLEASE tell me that there's a better way in Java to write this

DispatchingEffectsFromOptionValue.java

// findPrice : String -> Option<Price>
// Option comes from Atlassian's fugue library https://docs.atlassian.com/fugue/4.3.0/fugue/apidocs/index.html
// I want the equivalent of
// case (maybePrice) {
//   none => display.displayProductNotFoundMessage(barcode)
//   some(price) => display.displayPrice(price)
// }

catalog.findPrice(barcode)
        .<Runnable>fold(
                () -> (() -> display.displayProductNotFoundMessage(barcode)),
                (price) -> (() -> display.displayPrice(price))
        ).run();

@gtrefs Thank you. Yes. I have a separate project in which I'm rewriting my entire teaching example with the constraint "no method expectations in the tests", which encourages me to use return values in the way that you describe here (and even pushing Display up the call stack, where it becomes RenderResultView). In that situation, I think of the situation as mapping Option<Price> to Either<String, Price> and then to Either<ProductNotFoundMessage, ProductFoundMessage>. Now the Controller and View negotiate over who dispatches from the message alternatives to send the corresponding message text to the application's output stream.

This is not that project. I'm still using my old, OO approach (fire the right event for each outcome), but I found Fugue (and now Javaslang) intriguing, and so I'm trying to use them together. I can't tell whether the libraries are missing something useful or they're telling me that these types and the fire-event approach are fundamentally incompatible. That's one of the things I'm learning.

My two minutes attempt, using Functional Java. Obviously, untested and from the top of my head!

/* 
 * Assuming:
 *
 * barcode :: Barcode
 * display#displayProductNotFoundMessage() :: F<Barcode, IO<Unit>>
 * display#displayPrice() :: F<Price, IO<Unit>>
*/
catalog.findPrice(barcode) // Option<Price>
    .map(display.displayPrice()) // Option<IO<Unit>>
    .orSome(
	    display.displayProductNotFoundMessage().f(barcode) // IO<Unit>
	    )
    .run();

If the only side effect is printing a String, we could simplify it like this:

/* 
 * Assuming:
 *
 * barcode :: Barcode
 * display#displayProductNotFoundMessage() :: F<Barcode, String>
 * display#displayPrice() :: F<Price, String>
*/
String res = catalog.findPrice(barcode) // Option<Price>
    .map(display.displayPrice()) // Option<String>
    .orSome(
	    display.displayProductNotFoundMessage().f(barcode) // String
	    );
fancyPrint(res);