spec VS gc

You can parse many things from this file, what are you trying to extract?

https://github.com/WebAssembly/spec/blob/main/document/core/...

Still strikes me as super sad JS never got SIMD support. It seemed like there were some strong candidate specs. On Node there are some add-on npm libraries that implement.

My understanding was the main protest was that we would get wasm & some certain implementers said they wanted to focus their energy on wasm.

That was well over half a decade ago & wasm is still in incredible infancy, with basically only statically linked capabilities in the spec.

Wasm SIMD proposal itself only merged into wasm in November 2021. https://github.com/WebAssembly/spec/pull/1391

It seems really unfortunate to have decided to keep JS the slow inferior language.

Blazor and WASM itself (outside of dotnet) are relatively new tools and they already show impressive results. They will keep getting better with every release. E.g. this proposal https://github.com/WebAssembly/spec/blob/main/proposals/simd/SIMD.md which should bring WASM closer to "near native speed". Blazor already started working on it true.

Big fan of this author's work.

They have a Gameboy emulator written in C, which can be compiled to WASM and run in the browser.

https://github.com/binji/binjgb

I learned a lot from the code.

Also I love this project with a bunch of demos in hand-written WebAssembly Text (WAT) format, which is like low-level Lisp that works only with raw memory, numbers, and minimal syntax.

https://github.com/binji/raw-wasm

Then I discovered the same author is quite active in the WebAssembly ecosystem, including specs and tooling. Fascinating stuff!

https://github.com/WebAssembly/spec

https://github.com/WebAssembly/wabt

[The WebAssembly specification (https://webassembly.github.io/spec/) maintains that the standards apply to more than just the browser host, but also to any other compliant host runtime (what the specification refers to as an embedder).

Heya,

(1) Thank you for implementing this in JSC!! I hope they take it, it makes it into Safari, and the tail-call proposal advances.

(2) I don't think you are exactly right about the call stack being observable via thrown exceptions. There's no formal spec for the v3 exceptions proposal yet, but in the documents and tests, there's nothing that would change in WebAssembly core to make the call stack observable. It's true that the proposal amends the JS API (but only the JS API) to describe a traceStack=true option; from Wasm's perspective I understand that's just an ordinary exception that happens to include an externref value (just like any other value) to which Wasm itself attaches no special significance. The engine can attach a stack trace if it wants, but there's no requirement (here) about what that stack trace contains or whether some frames might have been optimized out.

(3) I think the real reason that a Wasm engine can't implicitly make tail calls proper is that the spec tests forbid it, basically because they didn't want the implementation base to split by having some engines perform an optimization that changes the space complexity of a program, which some programs would have started to depend on (the spec tests say: "Implementations are required to have every call consume some abstract resource towards exhausting some abstract finite limit, such that infinitely recursive test cases reliably trap in finite time. This is because otherwise applications could come to depend on it on those implementations and be incompatible with implementations that don't do it (or don't do it under the same circumstances.)" More discussion here: https://github.com/WebAssembly/spec/issues/150

The WASM paper discusses that in the final section: https://github.com/WebAssembly/spec/blob/master/papers/pldi2017.pdf

WebAssembly has a formal specification that includes both operational semantics and natural language-based descriptions of everything in the language. The official repository also has a lot of tests. Besides tests, you should be able to find lots of examples by searching.

It may take some time for WasmGC to be usable by .NET. Based on the discussions the first version of WasmGC does not have a good way to handle a few .NET specific scenarios, and said scenarios are "post-post-mvp". [0]

My concern, of course, is that there is not much incentive for those features to be added if .NET is the only platform that needs them... at that point having a form of 'include' (to where a specific GC version can just be cached and loaded by another WASM assembly) would be more useful, despite the pain it would create.

[0] - https://github.com/WebAssembly/gc/issues/77

Yes, that's definitely true: a single GC will not be optimal for everything, or even possible. Atm interior pointers are not supported at all, for example, but they are on the roadmap for later:

https://github.com/WebAssembly/gc/blob/main/proposals/gc/Pos...

What launched now is enough WasmGC to support a big and useful set of languages (Java, Kotlin, Dart, OCaml, Scheme), but a lot more work will be required here!

GC proposal is from 2018: https://github.com/WebAssembly/proposals/issues/16 and there’s code: https://github.com/WebAssembly/gc/blob/master/proposals/gc/O...

Seems like an awefully long time for progress to be made, given all the possibilities it would unlock.

First is the size. Writing a server-side and client-side program is possible with Rust, and the resulting WASM package will be small enough. At the same time, Microsoft Blazor converts C# code to WASM, but the client delivery has to include the reduced .NET runtime, taking several megabytes for a script. The same is true for GoLang, even with an attempt to reduce the runtime delivery in TinyGo WASM. Developers want to work with their favorite languages, whether it is Java, Kotlin, Dart, C#, F#, Swift, Ruby, Python, C, C++, GoLang, or Rust. These languages produce groups of runtimes. For example, JVM and .NET have many common parts, Ruby and Python are dynamically interpreted at runtime, and all mentioned depend on automatic garbage collection. For smaller WASM packages, browser vendors can include extended runtime implementations, for example, by delivering a general garbage collector as part of WASM. Garbage collection support by WASM is currently in progress: WASM GC, .NET WASM Notes.

My understanding is that the main limitation is technical. WASM doens't do GC or the host system calling conventions and cannot interact directly with object from Javascript because of this. However, this is being worked[0] on and will be solved eventually. Even without this the performance overhead of bridging to JS is low enough that WASM frameworks can beat out React.

0: https://github.com/WebAssembly/gc/blob/main/proposals/gc/Ove...

I’ve just watched a video on YouTube from Google I/O 2023 on Flutter for the web. Kevin Moore explains that Flutter can compile to Wasm, but now that GC support has been added to the standard and WasmGC is supported in Chromium and Firefox, I’m quite intrigued.

I have found the main thread about using WebAssembly GC in C#: https://github.com/WebAssembly/gc/issues/77. If I understand it correctly, it is not possible to use the current prototype version of GC in C#.

The .net team has given their notes on it, the concern is more on the memory layout from what I remember. Though it may be possible still. The runtime would likely still ship some gc code, but only a subset for cases not supported by the wasm gc itself and a few more for interfacing with the gc service, which overall should still result on smaller payloads compared to current sizes.

I assume that's one of the parts of the work done at https://github.com/WebAssembly/gc - not happening any soon yet, but it'll eventually be done.