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>> It's not like you can take a random JAR and convert it to WASM. Maybe you can: "TeaVM is an ahead-of-time compiler for Java bytecode that emits JavaScript

>> It's not like you can take a random JAR and convert it to WASM. Maybe you can: "TeaVM is an ahead-of-time compiler for Java bytecode that emits JavaScript and WebAssembly that runs in a browser. Its close relative is the well-known GWT. The main difference is that TeaVM does not require source code, only compiled class files. Moreover, the source code is not required to be Java, so TeaVM successfully compiles Kotlin and Scala." https://teavm.org/ https://teavm.org/ I have never had an opportunity to try out TeaVM, but it seems promising.

mike_hearn 4y ago
I've used TeaVM in a past project, to compile some Java to JS. It's very cool tech. Unfortunately I heard that the team ripped out the TeaVM after I left. That's understandable - I had to fix some bugs and missing pieces in TeaVM as part of that project, and I think a lot of codebases would face the same issue, but compiler hacking isn't everyone's, um, cup of tea. It was a great way to get a lot done in the two weeks I had available though. I should have clarified. Yes, you can probably do a native-image style "compile an app+embedded JVM to wasm" by pretending V8 is a CPU. There are programs that do that sort of thing, I think Leaning Technologies makes one. That wouldn't be of use in any existing Java project though. The only reason you'd ever want to do that is because browsers offer nothing else, even though they could and at that point why not compile to JS, at least that way your GC isn't being interpreted too. If you're not constrained by the WHATWG's decisions though it doesn't offer anything.
- thesuperbigfrog 4y ago
  >> There are programs that do that sort of thing, I think Leaning Technologies makes one. It looks like you mean CheerpJ: https://leaningtech.com/cheerpj/ https://leaningtech.com/cheerpj/ https://github.com/leaningtech/cheerpj-meta https://github.com/leaningtech/cheerpj-meta >> That wouldn't be of use in any existing Java project though. The only reason you'd ever want to do that is because browsers offer nothing else, even though they could and at that point why not compile to JS, at least that way your GC isn't being interpreted too. If you're not constrained by the WHATWG's decisions though it doesn't offer anything. It is very use case and "what is the future of your Java application" dependent. Some organizations are looking into migrating off of Java due to a variety of reasons. These kind of "Java conversion" tools help to keep legacy Java applications running until the legacy Java applications can be replaced.

mike_hearn 4y ago

I've used TeaVM in a past project, to compile some Java to JS. It's very cool tech. Unfortunately I heard that the team ripped out the TeaVM after I left. That's understandable - I had to fix some bugs and missing pieces in TeaVM as part of that project, and I think a lot of codebases would face the same issue, but compiler hacking isn't everyone's, um, cup of tea. It was a great way to get a lot done in the two weeks I had available though. I should have clarified. Yes, you can probably do a native-image style "compile an app+embedded JVM to wasm" by pretending V8 is a CPU. There are programs that do that sort of thing, I think Leaning Technologies makes one. That wouldn't be of use in any existing Java project though. The only reason you'd ever want to do that is because browsers offer nothing else, even though they could and at that point why not compile to JS, at least that way your GC isn't being interpreted too. If you're not constrained by the WHATWG's decisions though it doesn't offer anything.

thesuperbigfrog 4y ago
>> There are programs that do that sort of thing, I think Leaning Technologies makes one. It looks like you mean CheerpJ: https://leaningtech.com/cheerpj/ https://leaningtech.com/cheerpj/ https://github.com/leaningtech/cheerpj-meta https://github.com/leaningtech/cheerpj-meta >> That wouldn't be of use in any existing Java project though. The only reason you'd ever want to do that is because browsers offer nothing else, even though they could and at that point why not compile to JS, at least that way your GC isn't being interpreted too. If you're not constrained by the WHATWG's decisions though it doesn't offer anything. It is very use case and "what is the future of your Java application" dependent. Some organizations are looking into migrating off of Java due to a variety of reasons. These kind of "Java conversion" tools help to keep legacy Java applications running until the legacy Java applications can be replaced.