cel-spec VS simplelanguage

My employer uses a combination of Protocol Buffers (for the config schema definition) and Bazel/Starlark (for concrete instantiations). Configs are validated at build time and runtime using CEL (https://github.com/google/cel-spec).

The Common Expression Language (CEL) implements common semantics for expression evaluation, enabling different applications to more easily interoperate. https://github.com/google/cel-spec

Looks like Google invented a specification for a simple "expression language." -> https://github.com/google/cel-spec/blob/master/doc/langdef.md. Writing the expressions feels like writing Java, C++, Go, or TypeScript code. Google then released C++ and Go versions of this langauge as a library.

https://github.com/google/cel-spec unfortunately, it's in Go or C++. Of course I can write a binding to them. But is there any other similar that you would know of for Java? My other course of action would be to offload computation to another service using this library in Go, or Jsonnet or Open Policy Agent/Rego based evaluation, which I'd prefer not to. Executing JS in Java via Nashorn also an option but it'd be heavy weight.

Having a standard way to share expressions does seem quite useful, especially when it's multilingual.

[0]: https://github.com/google/cel-spec

There's more information about CEL and its specifications here

Especially when dealing with more complex match rules, I personally much prefer Caddy's matchers over building some weird-ass if constructs in Nginx. It also supports CEL for request matching, giving you access to extremely powerful logic, if you need it.

That sort of stuff is easy to do with Truffle (which, ironically, lets you define a language using what they call the "truffle dsl").

The SimpleLanguage tutorial language has a bigint style number scheme with efficient optimization:

https://github.com/graalvm/simplelanguage/blob/master/langua...

Truffle has no opinion on how you parse the sources. It cares about how you execute them from an intermediate Truffle guided representation produced by the parser.

In other words antlr and truffle are a great fit. We even use this pairing for our example language simplelanguage.

https://github.com/graalvm/simplelanguage

Do you have any feedback on how we could improve the docs? If so, please let us know!

I believe the easiest way to start a new Truffle language implementation is to fork SimpleLanguage [1] and turn it into your language. Did you try to do that?

[1] https://github.com/graalvm/simplelanguage

Finally, I would suggest you to take a look at the Truffle/GraalVM ecosystem(https://www.graalvm.org/graalvm-as-a-platform/language-implementation-framework/). The documentation is not exactly very elaborate, but a few good resources are Mumbler(http://cesquivias.github.io/blog/2014/10/13/writing-a-language-in-truffle-part-1-a-simple-slow-interpreter/#mumbler-language), SimpleLanguage(https://github.com/graalvm/simplelanguage), and (https://www.endoflineblog.com/graal-truffle-tutorial-part-4-parsing-and-the-trufflelanguage-class).