How to implement custom serializer for functools.partial?

[Jasha10]

How would I implement a custom serializer / deserializer for functools.partial objects?
My naive attempt is giving me an error

# serde_partial.py
from datetime import timedelta
from plum import dispatch
from functools import partial
from typing import Type, Any
import serde
from serde.json import to_json, from_json

class Serializer:
    @dispatch
    def serialize(self, value: partial) -> Any:
        return {
            "type": "partial",
            "func": value.func.__name__,
            "args": value.args,
            "kwargs": value.keywords
        }

class Deserializer:
    @dispatch
    def deserialize(self, cls: Type[partial], value: Any) -> partial:
        return partial(value["func"], *value["args"], **value["kwargs"])

serde.add_serializer(Serializer())
serde.add_deserializer(Deserializer())

to_json(partial(sum))

$ python serde_partial.py
Traceback (most recent call last):
  File "/home/homestar/tmp/serde_partial.py", line 27, in <module>
    to_json(partial(sum))
  File "/home/homestar/tmp/.direnv/python-3.10/lib/python3.10/site-packages/serde/json.py", line 74, in to_json
    return se.serialize(
  File "/home/homestar/tmp/.direnv/python-3.10/lib/python3.10/site-packages/serde/json.py", line 44, in serialize
    return json_dumps(obj, **opts)
  File "/home/homestar/tmp/.direnv/python-3.10/lib/python3.10/site-packages/serde/json.py", line 18, in json_dumps
    return orjson.dumps(obj, **opts).decode()  # type: ignore
TypeError: Type is not JSON serializable: functools.partial

[Jasha10]

I think the root of the problem is that custom serializers don't work at the top level. Closing this discussion in favor of #514.