Why not treat as object when mixing key types?

[subsoap]

And then allow numbers for keys too, is there a technical reason why it shouldn't be done?

[rxi]

Can you provide any examples of where this behaviour would be useful?

The library encodes the input value you provide as JSON — if it converted numbers to strings the JSON would no longer represents the data you provided. If you decoded it it wouldn't be the same data that you started with. I can't think of a scenario where this kind of automatic conversion would be beneficial.

[subsoap]

Yeah, you're right.

In my use case, I'm using this to convert tables into strings which can then be obfuscated back and forth and then converted back to tables from strings. I'll probably make a modified version which can allow the mixed keys and just assume that strings from the JSON which are numeric are to be numbers as keys in the tables.

[rxi]

If you're only using the serialised data with your own program and don't need a standard format you might be better served using something like serpent. This would allow you to serialise data that wouldn't be directly mappable to JSON, such as tables with non-string key types.