starlark-go VS goja

Starlark in go https://github.com/google/starlark-go is a great way to combine the best of both, the ease of use of Python and the simplicity of go.

I have been building a platform for deploying internal web applications using this approach https://github.com/claceio/clace. Use Starlark to configure the application, the platform itself is built in go.

The big unknown is your task definition: what does user-defined logic look like? If you're expecting go code, that's gonna need some cleverness because of the compiled nature of it. There's a node runtime implemented in go if you want to provide sandboxed javascript (check the source of k6.io, it's the main one I know that uses it). If you want to provide building blocks and let them compose them, starlark might be a good choice.

Another one of those (with broader language support) is the Starlark language, which has a Go implementation: https://github.com/google/starlark-go

Every config format gets as complex to be touring complete in the end. We had similar problems and eventually got rid of that complexity and switched to starlark (the bazel config language), was a huge benefit for the tools. https://github.com/google/starlark-go "Starlark is a dialect of Python intended for use as a configuration language. Like Python, it is an untyped dynamic language with high-level data types, first-class functions with lexical scope, and garbage collection."

Direct link to the Go implementation of Starlark: https://github.com/google/starlark-go

For a Python-like syntax, https://github.com/google/starlark-go is the language used in Babel. It's very mature, but since it is used in a massive mature project with a specific purpose, it doesn't move fast or drift from the spec of its Java-based sibling. It doesn't have exception try except blocks or some other features you might expect, but for short extension logic, it might be exactly what you want with the stability you can depend upon.

Context: https://github.com/google/starlark-go/blob/cfacd890221418a2dc2c736f7b5e3476c38709b1/starlark/int_posix64.go

Thus envd is more like Dockerfile, while it uses a simplified python dialect starlark https://github.com/google/starlark-go as the build language.

Use Go (mostly for starlark-go)

dop251/goja

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Apparently "not depending on Node or V8" means depending on some random Go JS engine instead.

Goja https://github.com/dop251/goja

Either call a JavaScript interpreter like node with exec.Command and read its stdout, or use a pure Go JavaScript interpreter like goja or otto.

Just to also say this is implemented in pure Go we aren't including V8 or any external dependencies we instead use https://github.com/dop251/goja which is a JS VM written completely in Go.

If you want to serialize a function to JSON one idea may be to embed a scripting language like JavaScript into your program. The goja package is a very good solution: a native ES5 JavaScript (with some ES6 syntax support as well) natively implemented in Go so you can get tight data bindings to your Go types and funcs. For your JSON marshalling you could serialize a JavaScript function source (text) and when reloading that, parse that text with goja to be able to run it dynamically in your Go program. Basically you'd need to get away from pure Go for this and towards something that is JSON compatible to (de)serialize to text.

Not really. It was built in-house and I don't know of anything about it that went public. I recall it using Goja for the JS runtime. Code was embedded into the binary (think embed package). There was some kind of sorcery to convert what would be HTTP network calls in the browser into local function calls during SSR, but I'm hazy on how it worked I'm afraid.