json5 VS starlark-rust

JSON5 support

Meanwhile, formats have been evolving (JSON5, YAML), config entry points are constantly changing. These fluctuations, fortunately, were covered by tools like the cosmiconfig.

I think JSON5 is fairly close to this: https://json5.org

I reckon the only thing it's missing to be truly accessible to non-techies is that string values still need to be quoted, i.e. you can't have:

key: this is my value

(I'm definitely not saying it would be a good idea to allow quotes to be dropped, just that that's the only potential stumbling block I see for non-techies.)

I believe that's JSON5.

https://github.com/json5/json5

It's my preferred configuration file format, it fixes all the problems I have with JSON (trailing commas, comments) without turning it into a mess full of gotchas like YAML.

JSON 5 support

I would like to see mention of JSON5 which is 11 years its elder. For comments in JSON, JSON5 is a good starting point.

I haven't seen anyone mention starlark yet. It's something I want to play with as a config language.

Aside from these, if you want some inspiration for a production-grade language built in Rust, you might want to go through the source code of Starlark and Gluon.

There is also a Rust implementation of Starlark as a starting point https://github.com/facebookexperimental/starlark-rust

To add to everyone else, please don't use YAML. Starlark is great _precisely_ because it is a readable, well known (nearly Python) language that is limited at the same time (no unbounded for loops, no way to do non-deterministic things like get the current time or `random()`).

This is a follow-up to Benchmarking mlua/rlua/rhai - Rust embedded scripting languages from 4mo ago; I just added the new Starlark implementation from Meta to the benchmark posted by @aleksru.

The Rust implementation has it as an experimental extension (https://github.com/facebookexperimental/starlark-rust/blob/m...)

u/ndmitchell has been working on a Starlark interpreter. He wrote up a blog post with some thoughts about different interpreter styles. He found that in his case using fixed sized instructions was about the same as byte-encoded ones, but compiling the AST to closures was also about the same performance as well, and doesn't need an AST->bytecode compiler.

As mentioned in other comments, type system features like algebraic data types (that Rust has) are really helpful. If you want a small-but-real example of a compiler in Rust (with an optimizer etc) then the starlark-rust compiler is good.

If your Rust program needs a more complicated configuration (conditionals, access to APIs and so on), also look at Facebook's Starlark parser and tooling[1]. Starlark is a subset of Python used by Bazel, Buck and a few other projects.

[1]: https://github.com/facebookexperimental/starlark-rust

The Facebook post gives a nice overview. It also links out to the home page for the project at https://github.com/facebookexperimental/starlark-rust/, which has an introduction and links to what Starlark is, the crates.io link, the docs.rs link etc.