Comment by hutteman | Hacker News Reader

Comment by hutteman | Hacker News Reader

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I would say in most cases: no.

Due to backwards compatibility concerns, no existing Java APIs that may currently return null can ever be changed to return Optionals instead, so nulls need to be dealt with regardless. Also, there's technically nothing stopping an Optional value from actually being null itself, or from developers calling Optional.get() without checking isPresent(), just like they might currently use a reference without checking for null.

I personally really wish jsr305 had been adopted in Java8, and their existing APIs retrofitted with these annotations.

http://www.oracle.com/technetwork/articles/java/java8-option... describes Optional, and compares it to how in Groovy, the safe navigation and elvis operators allow you to write code like this:

   String version = computer?.getSoundcard()?.getUSB()?.getVersion() ?: "UNKNOWN";

With Java 8 Optionals, this instead becomes:

   String version = computer.flatMap(Computer::getSoundcard)
                            .flatMap(Soundcard::getUSB)
                            .map(USB::getVersion)
                            .orElse("UNKNOWN");

which is not only much longer and arguably uglier, but also forces developers to suddenly have to worry about applying lambdas using flatmap vs map, where conceptually you're really just dealing with method calls.

New languages like Kotlin solve this much better in my opinion by introducing nullable vs nonnullable types. While Java can unfortunately never adopt this due to backwards compatibility issues, @Nullable and @Nonnull will do most of the time, and hopefully we'll see operators like ?. and ?: in future versions of Java.

While I've enjoyed the Elvis operator in Groovy, the point of optional is to make null go away altogether. In Groovy, you are never guaranteed anything isn't null, so the end result is that you will Elvis everything. While this is easier than the good old if statements, you are still paying for the penalty of a billion ifs in bytecode.

With option, you clearly declare what is safe, and what isn't, and the compiler won't let you screw up. You can decide which layer of your code handles the empty case, and lots of unnecessary ifs go away from the bytecode itself, so the app will run faster, and you know when you have to even consider the null case.

Now, doing that in Groovy is rather silly, because your language is dynamic and your types are optional, so all of this compile time safety would not provide any value anyway. Option is just the way you'd solve the problem in the strongly typed way. It's how you handle it in Scala, for instance, and how Haskell would deal with it.

As far as using flatmaps and maps to work with optionals, yes, it's a chore. I'd argue it's borderline abuse of the stream operators, as treating Option as a collection is ugly. That said, putting yourself in a situation where you chain 3 optional getters is also object design from hell, so one should avoid putting themselves in that position altogether.

In Scala, instead of flatmapping single optionals, we often getOrElse(), or use pattern matching as an extractor. Now that's a feature I would like to see Java 'steal' from the Scalas and Erlangs of the world, but I do not see that happening.

> in Groovy, the safe navigation and elvis operators

The elvis op is called the null coalescing op in other languages. [1] Groovy's promoter chose the elvis name to fit in with marketing the Groovy and G-String names.

PHP also uses the ?: symbol but other languages use different ones, e.g. C# uses ?? and Perl uses //

[1] http://en.wikipedia.org/wiki/Null_coalescing_operator

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