Consider a JSON object

{ 
   "with-hyphen": "a-string", 
   "$startsWithDollarSign": 123
}

Problem: It's not possible to provide type-hints for with-hyphen and $startsWithDolalrSign

CEL can get type information well if we can express an object as protobuf, or use StructType. However, there are times when we have objects that have non-identifier keys.

Right now, it's not possible to provide typesafety for non-identifier keys.

It would be amazing if we could.

Alternatives considered

To solve this for ourselves, we considered to hacks:

1. Use aliases: walk the CEL tree, and rename all non-identifer keys to some known identifer-style key.
2. Run our own compile step validation: walk the cel tree, and do the type checking ourselves.

Right now we are going with 2., but if there was some built-in way to specify types for keys from index access, it would be amazing.