Serializers for JSON object keys

[Ericson2314]

Basically, I am looking for the equivalent of https://hackage.haskell.org/package/aeson-2.2.3.0/docs/Data-Aeson-Types.html#t:ToJSONKey

I would have assumed that Serde had some prior art for this too, but maybe it does not.

[nlohmann]

There's no dedicated 'key serializer' customization point analogous to Haskell's ToJSONKey/FromJSONKey — the closest existing mechanism is specializing adl_serializer for the value type, but object keys are always treated as (or converted to/from) std::string without a pluggable hook. This is a legitimate, if fairly niche, extension-point gap; it would mostly matter for users with non-string-like key types (enums, strong-typedefs) who want customizable key (de)serialization beyond what NLOHMANN_JSON_SERIALIZE_ENUM already covers.

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This reply was drafted by Claude Code on behalf of @nlohmann, as part of a review of open discussions.