Discussion & feedback

[orangemug]

I would appreciate feedback on this tiny language for mapbox-gl-js expressions (see the main README.md for details).

If you like it or hate it please tell me why. Thanks in advanced! 😊

[orangemug]

@pjsier continuing from your comment in maplibre/maputnik#200 (comment) the thought of writing JSON for mapbox-gl-js expressions seemed like pain to me. So I thought I'd have a go at writing a tiny language instead.

I would love to know your thoughts.

[pjsier]

@orangemug I think this could be really useful as a standalone project since the Mapbox style spec syntax is really verbose, but I'm hesitant about including it as part of Maputnik.

The style spec is already a bit of a moving target and changing really frequently, so keeping this up to date with their changes could be a challenge. I could also see it being confusing for people to use a separate syntax on Maputnik.

That said, I can see this being really useful for using a lot properties and expressions in the code because they can get unwieldy, so really well done!

[orangemug]

Thanks for the feedback @pjsier.

so keeping this up to date with their changes could be a challenge

A few more details for you, incase you're interested, no worries if not.

There is actually not a lot tying it to the expression spec, that was the aim anyway. Basically the only bit that needs to stay constant for it to keep working is that a function is defined in this way

[function_name, arg_1, arg_2, arg_3...]

There are also a two other opt in syntax sugar

• ["get", FEATURE_NAME] which has a shorthand @FEATURE_NAME
• ["let", ...] and ["var", VAR_NAME]

It's the job of mapbox-gl-js to decide if the JSON is correct or not. The expression JSON can also be decompiled to code (almost there with this). So you can basically toggle between simple-expr and JSON

Thanks again for the feedback

[orangemug]

Added source maps, see https://orangemug.github.io/simple-expr/fmt.html