Java sealed classes and exhaustive pattern matching

(neilmadden.blog)

31 points | by hnisjafx40 2 hours ago

3 comments

  • timshel2 9 minutes ago
    Scala punching the air rn
  • armchairhacker 1 hour ago
    Java also has recursive patterns and (maybe still in preview) literal patterns: `switch (x) { case A(B(true, var c)) -> f(c); }`
  • Larrikin 1 hour ago
    Java continues to try and catch up to Kotlin https://kotlinlang.org/docs/sealed-classes.html

    I didn't mind Java when the comparisons were to C++, Ruby, and Python. I can not find a reason to go back after Scala (which seemed to fail due to being indiscriminate) and especially Kotlin

    • DarkNova6 4 minutes ago
      What I like about Java is that it is a deliberate late-mover language. It doesn't go for the latest shiny thing but looks at what features have proven themselves in other languages.

      I can't help but to be a little sobered by the promises of Kotlin and C#. They look great on the surface, but once you have more complicated code to work on they tend to show warts quite fast.

      Java is remarkably consistent and really doesn't have any sharp edges. Even with generics and type erasure, I found myself fighting the language semantics in C# way more often than Java.

    • pron 6 minutes ago
      A hoarder has much more furniture than I do, but if I buy a sofa it certainly doesn't mean I'm trying to catch up with the hoarder (who has five). Java isn't trying to catch up for the simple reason that we don't want it to have all the features Kotlin does; in fact, we're trying very hard to avoid that (not to mention that we have yet to adopt a single Kotlin feature; our features usually take a different form, even though Kotlin, Java, and many other languages often rely on the same inspiration, which is usually the ML language). That's because some languages aim to be feature-rich while others aim to be more minimal. Both are likely to accumulate features over time, but at very different rates (we'll hold off on features for years until we're satisfied that their value justifies the added complexity to the language, as keeping that relatively low is very important to us).

      If you like a richer language, the Java platform offers you options, but many people prefer smaller languages (the number of Java Platform developers who use the Java language has remained pretty much at a constant ~90% for the past 15 or more years), but we're aware that a non-tiny minority of developers prefer richer languages, and so we accommodate them, too. Either way, 95% of the JDK is runtime (standard library and the JVM) and tooling, and you'll enjoy it regardless of which frontend language you prefer.

    • sideeffffect 35 minutes ago
      > Java continues to try and catch up to Kotlin

      Does it, really? Java has had pattern matching since 21 (2023). Kotlin still, to this day, the year of our Lord 2026, doesn't...

    • troupo 13 minutes ago
      Of all languages the only one it's trying to catch up to (and in places outran) is C#

      With many others it doesn't compete because it would need a from-scratch rewrite of the runtime (Erlang/Elixir), or a from-scratch redesign of the type system (Rust, perhaps Swift).