Yeah I actually haven't found a great answer yet. Here's everything I've tried and why it sucks:
* JSON. No comments. Deal-breaker
* JSONC. No unique file extension so its difficult to distinguish from JSON. Poor library support due to library authors drinking the "comments are bad" koolaid.
* JSON5. This would be an excellent option IMO except that library and IDE support is not great.
* JSON6. This just complicates JSON5 for minimal benefits. Pointless.
* Cue. As described.
* Jsonnet. Pretty good option tbh! However I couldn't get the Rust library to work. It's a low level parser, seems like you can't just plug it into Serde, which is what 99% of people really want. Also I ran into the "uncanny valley" effect where you can do some things but not all. So it tricks you into writing some programmatic config (e.g. with string manipulation) but then you find you can't do that string manipulation.
* Dhall. Weird syntax (backslash to declare functions. I've also heard it is slow. Didn't try this too much.
* YAML. Obviously YAML is the worst option. However I did realise you can use it as basically JSON5 except with a different comment character, which is not too bad.
* Starlark. Actually I haven't tried this yet but it looks promising.
So yeah I have no idea at the moment.
I wonder if it would be worth defining a "YAML JSON5" format, that's basically YAML-compatible JSON5.
Ha I forgot about that. TOML is pretty awful too. It's fine as long as you only need 1 level of nesting. As soon as you need to go deeper than that you end up with [[weird syntax]] that is very not obvious. I would say it's less obvious than YAML and YAML is already pretty unintuitive.
* JSON. No comments. Deal-breaker
* JSONC. No unique file extension so its difficult to distinguish from JSON. Poor library support due to library authors drinking the "comments are bad" koolaid.
* JSON5. This would be an excellent option IMO except that library and IDE support is not great.
* JSON6. This just complicates JSON5 for minimal benefits. Pointless.
* Cue. As described.
* Jsonnet. Pretty good option tbh! However I couldn't get the Rust library to work. It's a low level parser, seems like you can't just plug it into Serde, which is what 99% of people really want. Also I ran into the "uncanny valley" effect where you can do some things but not all. So it tricks you into writing some programmatic config (e.g. with string manipulation) but then you find you can't do that string manipulation.
* Dhall. Weird syntax (backslash to declare functions. I've also heard it is slow. Didn't try this too much.
* YAML. Obviously YAML is the worst option. However I did realise you can use it as basically JSON5 except with a different comment character, which is not too bad.
* Starlark. Actually I haven't tried this yet but it looks promising.
So yeah I have no idea at the moment.
I wonder if it would be worth defining a "YAML JSON5" format, that's basically YAML-compatible JSON5.