expressive-java VS Immutables

With JDK17 and the introduction of Record types, sealed classes/interfaces, and pattern-matching the implementation can come close to ver-batim mirroring the Scala 2 one: - Scala: https://www.scala-lang.org/old/node/56.html - JDK 17 Java: https://github.com/Randgalt/expressive-java/blob/master/java-17/src/main/java/examples/SimpleInterpreter.java

I wanted to share this little project I found. The author has been writing Java re-implementations of the same Scala interpreter over the years as newer JDK versions & features are released.

With JDK17 and the introduction of Record types, sealed classes/interfaces, and pattern-matching the implementation can come close to ver-batim mirroring the Scala 2 one:

https://github.com/Randgalt/expressive-java/blob/master/java...

Unfortunately, the Scala org website is down right now, so the original code can be viewed here for the moment:

https://web.archive.org/web/20200103022853/https://www.scala...

(Or also in the repo: https://github.com/Randgalt/expressive-java/blob/master/scal...)

The final feature that is needed to really seal the deal, is part of JEP 405 for destructuring + binding to values in patterns ("Deconstruction patterns"):

https://github.com/Randgalt/expressive-java/issues/3

https://openjdk.java.net/jeps/405

using records and ADTs (sealed types) with pattern match "switch" and the net result is an almost verbatim translation.

https://github.com/Randgalt/expressive-java/issues/1

There is one ugly line which JDK18 will fix, "destructuring in pattern captures/match".

This is every Lombok lover's favorite strawman argument I've run into.

I've been coding in Java professionally for ~20 years. I can count with zero hands the number of times I've been burned by a getter or setter getting changed into something surprising.

If you really need auto-generated getters/setters/builders - Immutables [1] is a library that does it using bog standard annotation processing rules that don't require hacking your build process.

[1] https://github.com/immutables/immutables

https://github.com/immutables/immutables/issues/1358 https://bugs.openjdk.java.net/browse/JDK-8281238

That's good, but I prefer this : https://github.com/immutables/immutables It has all sorts of neat stuff like lazy, defered, cached, defaults etc. Just needs updating to use records.

Not bad :) I like using Immutables (which is backed by the style of implementation referenced in the link in https://github.com/immutables/immutables/issues/450)

Annotation processors? Like Immutables? Those already exists, but the major difference is that an annotation processor cannot change the processed class, but has to create another one.

While you’re looking into this I would highly recommend checking out immutables. https://github.com/immutables/immutables It is pretty popular in the industry and very nice!