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Comment by samsquire | Hacker News Reader

This is exciting.

I think WASM is an example of a thin waist [1] with its garbage collector and N+M rather than N×M. (N languages + M virtual machines + G garbage collectors). That's a mature garbage collector in V8.

I was curious if there was a WASM to JVM and it seems there is one on GitHub, I haven't used it I was just curious because the JVM is a mature (and parallel) garbage collector.

Now I'm excited for WASM Threads for true parallelism and not just IO parallelism because I didn't think WASMGC would come out so soon.

The opportunity to solve async and parallelism and garbage collection EFFECTIVELY would strengthen WASM and not be a source of confusion or difficulty for developers. I think that's why WASI is so important, a chance to define an API as stable as POSIX.

1: https://www.oilshell.org/blog/2022/02/diagrams.html

2: https://github.com/cretz/asmble

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> I was curious if there was a WASM to JVM and it seems there is one on GitHub [...] https://github.com/cretz/asmble

While it works well, this was mostly a fun project for me and I no longer really maintain it. I hope that the ideas and explanations of how I mapped WASM IR to JVM bytecodes helps whoever does build this in a more official capacity. I don't have any plans to support WASM GC currently.

GraalVM can run WASM executables: https://www.graalvm.org/latest/reference-manual/wasm/

Following CLR footsteps, 22 years later.

> More than 20 programming tools vendors offer some 26 programming languages — including C++, Perl, Python, Java, COBOL, RPG and Haskell — on .NET.

From https://news.microsoft.com/2001/10/22/massive-industry-and-d...

I don't really know where to place this comment. Multi-language systems existed before, therefore Wasm should not, because it's already been done?

It's interesting that none of the languages that you list made .NET a primary target and have all either bit-rotted unofficial ports or sunsetted their mainline support. It's hard to say whether languages that now target Wasm will suffer the same fate, since that depends on level of maintenance that each project allocates to particular targets. Still, I don't really get your point.

The usual amazement as if WASM was the first at anything...

Being first rarely matters. Good execution at the right time is the crucial part.

And maybe not being the start of another MS embrace-extend-extinguish ploy.

People know VMs existed before WASM

If only the CLR had followed CLR footsteps as well, but they didn't even try after the DLR. Most non-Roslyn languages can barely interact with modern C# or the newer build configurations; even F# is playing catch-up and they're part of the official toolchain.

That is the sin of guest languages, that is why C rules on UNIX, JavaScript on Web, Java on the JVM, C# on the CLR, ....

Every guest language means additional IDE plugins with platform knowledge, since most communities want idiomatic libraries, an ecosystem on top of the ecosystem, as the actual platform is only implemented in a main "systems" language, mastering it is required anyway for all the leaky abstractions on the platform, additional build toolchains,...

In the end, each polyglot platform achieves a global maximum of main language, and possibly a winner among all guest languages, even if it takes a couple of years with projects fading away until this happens.

It sucks, however so it is the outcome of human nature attention span, and not being able to keep momentum for all languages across the whole lifetime of a given platform.

It seems like the JVM has been more successful than most platforms at supporting other guest languages. Java is still dominant, but Kotlin's pretty popular (as other comments have mentioned) and Scala has a nontrivial amount of usage. I think JRuby's also used some, but I'm not sure.

Arguably a perspective here is not that the JVM is more successful but that simply that Java as a language is less successful/more deficient language than C# and leaves more evolutionary niches available for other languages to coexist in its ecosystem, whereas C# checks more boxes generally. One reading of the history of Kotlin is that is almost directly the reason for Kotlin's existence in the first place because Java itself fell so far behind C# state of the art.

The DLR made it much easier for dynamic languages on .NET to interact and share infrastructure on top of the CLR, but it also gave C# directly just enough dynamic language powers that filled most people's use cases for that niche.

Even in the current race between C# and F#, unless you are using features such as Units of Measure or Type Providers, there is often a sense of "you don't need to use F# because that feature will be eventually in C# anyway" and "F# is just a proving ground for C# ideas". The F# community continues to try to find marketing messages that aren't that and better highlight some of the niches that F# can fill that C# won't. The most recent attempts have been trying to position F# as a "data sciences" language useful for Notebook-driven development in direct comparison/competition to Python/R/Julia. C# actually is finally useful in Notebooks now and has some alright REPL support, but F# likely will always better fit that niche. It will be interesting to see if that marketing approach helps.

> It seems like the JVM has been more successful than most platforms at supporting other guest languages

I think that’s more because of the amount of good Java binaries than because the JVM is good at supporting alternative languages.

Scala had to make a few design choices they would never have made if they didn’t want to target the JVM and be compatible with existing Java binaries.

Examples:

- having Option[T], but still having null, too.

- value types aren’t supported in the JVM (yet), so they’ve had to implement them using classes.

- scala’s reflection would have been easier to understand if they could have tweaked the JVM to implement it (scala had to work hard to map its type system to that of the JVM)

- scala has its own integer classes that are subtly different from both Java’s value types and it’s integer classes.

Kotlin mostly is Java with a different syntax. Like scala, it must be doing some magic to support its value classes.

Also, as another post in this thread said, some languages my need a garbage collector that behaves different from the JVM one. If so, you either adapt, or give up running on the JVM.

Scala 3 has an option to exempt null from ordinary types, marking nullable types as T | None, so this is not related to the JVM, this can be completely decidable at compile type.

The reflection claim is also questionable, as Scala used to be available for the CLR as well, but that version was abandoned, while the JVM is striving. In fact, erasure of generics help with guest languages, as it doesn’t bake into the variance.

> Scala 3 has an option to exempt null from ordinary types, marking nullable types as T | None, so this is not related to the JVM

I don’t know scala 3 well, but if it can make nonnullable types (that’s what “exempt null from ordinary types” means, isn’t it?), that’s not something the JVM knows about (although that may be changing with the addition of value types to the JVM)

Even if that’s incorrect, there are plenty of other examples of types that map badly to the JVM, such as Either[String,String] and AnyVal (a scala class with subclasses such as Int)

Another example are value classes, which are values until they aren’t. https://docs.scala-lang.org/overviews/core/value-classes.htm...:

“Universal traits allow basic inheritance of methods for value classes, but they incur the overhead of allocation”

And yes, scala3 has opaque types, but in the JVM, those must revert to their underlying type (if they don’t, the performance gains are lost), and scala3 also still has value classes.

> this can be completely decidable at compile time.

It can’t the moment you load a jar and call a method in it, and I think about every scala program does that.

> The reflection claim is also questionable

The JVM has strict single inheritance. Scala supports a form of multiple inheritance through traits. There’s no trivial way to map that to the JVM.

> In fact, erasure of generics help with guest languages, as it doesn’t bake into the variance.

I don’t understand that. It surely doesn’t always help. Scala reflection doesn’t want erasure, so they’ve had to work around that.

> I don’t know scala 3 well, but if it can make nonnullable types (that’s what “exempt null from ordinary types” means, isn’t it?), that’s not something the JVM knows about (although that may be changing with the addition of value types to the JVM)

Haskell or Rust compiles to machine code, which can have invalid/null pointers as well they don’t know about. Nullness is a so-called trivial property, the compiler can prove the absence of NPEs in code output by it, so you only have to check at the boundaries (e.g. every java method will return a nullable type)

I don’t know why would these map badly to java types. Scala unifies primitives with their boxed versions and tries to smartly optimize between them, so it doesn’t have the kind of distinction as Java. Value classes require runtime support so the only thing Scala can do is to alias a primitive as another class, but optimize it away. Of course this is a leaky abstraction, but this is a fact of life on managed runtimes.

Re multiple inheritance: doesn’t map natively, but this also doesn’t need native support. At worst, scala can always just go the Groovy way and intercept any call to/from every such object of theirs and then they can literally do any form of call indirection.

Re reflection: as far as I know Scala doesn’t really require frequent use of reflection, as it can circumvent it at most times through metaprogramming/more expressive language features. Also, type erasure is the norm — most runtimes don’t store type infos.

Kotlin is popular on Android, because Google says jump and everyone jumps.

All the other alternative languages had better times behind themselves.

Groovy survives thanks Jenkins and Gradle.

I think Kotlin is slowly eclipsing Java on the JVM. Its not majority yet but most new projects or major refactors I've seen are either 100% Kotlin or majority Kotlin.

I would not be surprised if Kotlin takes a majority share eventually

Kotlin is Java with minor syntax changes - it brings nothing new to the table and you write it the exact same way as you would Java. It's an easy sell for shops that want the feeling they're making forward progress in the field of computing but who don't actually want to change anything.

That’s factually wrong. Null-safety alone changes completely how you write Kotlin, add to that coroutines, extension functions and dozen other quality of life improvements and you get completely different style.

Nah, only on ART.

No JVM will ever be rewriten in Kotlin for it to matter outside Android.

Why would the JVM need to be rewritten in Kotlin for it to "matter"?

Kotlin is an official language of Spring, Vert.x, Micronaut, Gradle and IntelliJ platform. What are you talking about?

It feels to me a little bit like how geographic regions wind up working out dominant spoken/written languages.

The guest languages are like relying on (human or machine) speech/writing translation services to communicate with folks who only know the local lingua franca.

That added friction hobbles the minority languages.

Perhaps AI will aid in greatly reducing these issues over time (and I say this because large language translation models and text to speech + speech to text are finally reaching professional human quality while running on local hardware today). But I can't think of any other good method to hold back the floodgates of people being forced to choose between their mother tongue (with its corpus of invaluable baked in stories and perspectives) and being understood by others.

I was just looking at the status of IronPython, and it's on Python 3.4, which has been end-of-life for nearly five years. I'm not sure that indicates practical usability for most developers. Only C#, VB, and maybe F# actually seem like a safe choice on .NET. (PowerShell too, but that's a different use case.) So, just because something has been, or can be, done "in theory" doesn't mean all that much.

Unless you were intending this as a criticism of .NET?

I could see WASM actually pulling this off.

IronPython is indeed quite a pain to work with, and for a lot of reasons beyond the age. For instance, you don't get numpy or any dependencies that themselves depend on quirks of CPython. The alternative is PythonNET, which executes python in CPython context, but provides nearly the same interoperability* with CLR assemblies. There's many devils in the details of that asterisk, and I'm frankly not knowledgeable enough to explain them; but in my experience, things work well enough that I'm satisfied with the integration provided.

Where is my Haskell.NET? Dammit!

F#: https://learn.microsoft.com/en-sg/dotnet/fsharp/what-is-fsha...

EDIT: Yes, F# is an ML-style language. I was answering the spirit of the question, which was 'statically-typed functional-first programming language running on the .NET CLR'.

F# is ocaml.net not haskell.net

> I haven't used it I was just curious because the JVM is a mature (and parallel) garbage collector.

Slightly pedantic, but the JVM is a bit more than its arbage collectors[^1]. But it is true that the JVM has been the experimentation bed of garbage collection, not because academics have been specially daring with the JVM, but because JVM programs have been used extensively, and often so in ways that strain any single GC technique.

[^1]: https://www.baeldung.com/jvm-garbage-collectors. The Azul JVM also has its own, different one. And those are the ones I know of; I'm pretty sure I'm leaving quite a few out.

> Now I'm excited for WASM Threads for true parallelism

Pedantic: threads are concurrent, not necessarily parallel. It's weird to see them called "true parallelism". I assume you mean in comparison to coroutines, but those are sequential (their execution order may be arbitrary, but we can rely on them not being concurrent).

If wasm adopts threads that would be another unfortunate WorseIsBetter situation, given that threads are probably the worst model of concurrency we've ever devised (other than concurrent COMEFROM)!

> If wasm adopts threads that would be another unfortunate WorseIsBetter situation, given that threads are probably the worst model of concurrency we've ever devised (other than concurrent COMEFROM)!

Like it or not, threads are here to stay. Threads with shared mutable memory are the abstraction that multi-processor systems give software. They are not a software invention (anymore, as they might have been considered in the uniprocessor era).

A key goal of Wasm is to be a portable (and safe!) abstraction over hardware. Thus exposing extremely pervasive hardware abstractions like threads is well within its mission. Doing so safely has meant careful design and specification that captures what hardware gives for memory models without forcing a new programming model or undue burden on languages, toolchains, or runtimes.

Given that there are literally billions of lines of software that use threads, hardware actually implements threads, and the entire stack is driven to optimize threads, it would indeed be a bold move to impose a different abstraction at the Wasm level. An abstraction that would incidentally be immediately used to emulate threads. That's a real layering screwup--abstraction inversion.

Also, I think your pedantry is unwarranted and a distraction. Many people accept the claim that threads are "true parallelism" and would consider cooperative (or even green) threading systems to be "not what we meant when we said threads". It's just a red herring to go off and discuss technicalities when the context is clearly Wasm exposing hardware threads.

> An abstraction that would incidentally be immediately used to emulate threads.

That would be a win if performance was the same!

Maybe, but it's extremely rare that abstraction inversion results in the same performance. It's usually a big overhead.

If WASM adopts threads, and multithreaded wasm code is allowed to use GC features, then the GCs will suddenly need a bunch of work done on them.

> Now I'm excited for WASM Threads for true parallelism

Same, I'm very interested in using threads in the browser but sadly thus far threading in wasm on the browser requires the server providing an extremely restrictive response header making threads impractical for most applications.

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