> because they had to make it with almost perfect backwards compatibility for one of the most popular languages with trillions of lines of code produced over decades.
replyAt what cost? A key benefit of value types is improved performance but AFAIK Valhalla doesn't even let you pass them by reference. Efficiently passing them through registers is great but won't help you out with larger value types.
idk maybe java should adopt something similar to rust's "edition"?
replyCorrect me if I'm wrong, but Rust editions are a source code-level feature. So given you have the source code of newer and older rust code, you can compile them together.
replyThat's materially distinct from Java's model of basically dynamic loading already compiled class files. Though class files do have "editions", and there are extra code to deal with different versions. But still, it should be possible to e.g. send a new value class to an old library's class that has never heard of them, and that should just work.
The important thing is that Rust editions affect semantics and name resolution. In such an analogy, JVM bytecode is the equivalent of Rust code - various semantics are baked in, but stuff like name resolution isn't (at least not completely).
replyExcept of course they are breaking backwards compatibility, in relatively subtle ways, for anything that uses the standard library wrapper types. So every use of Integer, Boolean , etc is an opportunity for either a compilation error or a runtime bug.
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