How to use hako in Go?

[nickchomey]

Hey there, I came across hako from this comprehensive benchmark of js engines https://zoo.js.org/?arch=amd64

But they link to some old commit where you seemed to be using primjs, but now use a different fork of QuickJS. They linked to this gist https://gist.github.com/andrewmd5/197efb527ef40131c34ca12fd6d0a61e for using with Go. But there's no mention of that anymore in the main branch.

Is there a recommended way to use hako in Go? Should that benchmark be using it instead?

Thanks!

[joeblew999]

Wazero would the way I would try

[andrewmd5]

The main idea is to use Wazero + Go to write the calling abstraction for all the Hako exports. Then, link the necessary imports, such as the callbacks for host functions. Finally, design all the language-specific sugar to make everything more user-friendly.

In the QuickJS fork, you can find tooling that parses hako.h and generates a JSON definition. This JSON definition can be used to generate code for all the exports. You should be able to complete this task in about 30 minutes. If you want to add other features like the event loop, automatic promise resolution, and host functions (sync and async), these are largely host-level abstractions built around the Hako API. You can refer to the .NET host for more information.

Once everything comes together you should have a fully embedded JS engine with no external runtime dependencies.

So tl;dr use wazero to link imports, call exports, and write a lot of sugar so it meshes well with Go conventions. I can share a new sample in a bit.

[joeblew999]

The main idea is to use Wazero + Go to write the calling abstraction for all the Hako exports. Then, link the necessary imports, such as the callbacks for host functions. Finally, design all the language-specific sugar to make everything more user-friendly.

In the QuickJS fork, you can find tooling that parses hako.h and generates a JSON definition. This JSON definition can be used to generate code for all the exports. You should be able to complete this task in about 30 minutes. If you want to add other features like the event loop, automatic promise resolution, and host functions (sync and async), these are largely host-level abstractions built around the Hako API. You can refer to the .NET host for more information.

Once everything comes together you should have a fully embedded JS engine with no external runtime dependencies.

So tl;dr use wazero to link imports, call exports, and write a lot of sugar so it meshes well with Go conventions. I can share a new sample in a bit.

thanks @andrewmd5

I love how you managed to work out hosting inside dotnet. It's really cool how it's able to be embedded. I think I can get it working inside IOS and Android apps too if you are interested.

Would be fab to see that new sample. this is really a huge boost for some many projects that I work on. I think that this can be used for so many other use cases ...

[andrewmd5]

There's now a working Go host: https://github.com/6over3/hako/tree/go/hosts/go

It uses wazero and has the basic infrastructure working:

• Registry bindings auto-generated from engine/bindings.json via codegen.ts
• Runtime, Realm, and Value types mirroring the C# host structure
• EvalCode working (see example_test.go)
• CallbackManager with stub handlers ready to be implemented

rt, _ := hako.New(ctx, wasmBytes, nil)
defer rt.Close()

realm, _ := rt.CreateRealm()
defer realm.Close()

result, _ := realm.EvalCode("Hello, " + "World!")
defer result.Free()

fmt.Println(result.String()) // Hello, World!

Should be a good enough starting point to build a proper Go wrapper and abstraction. It isn't in my skillset / I don't have time, so if anyone wants to champion making it a Tier 1 language let me know.

The wazero setup has a couple quirks documented in runtime.go:

1. Needs experimental.CoreFeaturesTailCall enabled
2. Memory export requires a workaround since wazero's HostModuleBuilder can't export memory directly