Fixed a serialization bug in dspy.Example

[guydav]

Example.toDict() did not account for the case in which the value is a tuple. This happens in Evaluate.__call__(), where the results is a list of tuples, where each tuple includes Prediction objects internally. Right now, the failure to parse tuples means the internal Prediction objects do not get serialized to dicts, which means that the resultant dict is not, for example, json-serializable.

I opted for a minimal fix, but there could be other approaches, e.g. adding a dependency to handle the serialization, etc.

[chenmoneygithub]

Thanks for the PR!

I am a bit confused about the case where you see errors though, are you trying to serialize the entire evaluation result? That shouldn't be a dspy.Example. Could you include a reproduce code snippet?

[guydav]

Hi @chenmoneygithub -- tl:dr; everything inherits from dspy.Example. Evaluate.__call__ returns the following:

EvaluationResult(
    score=round(100 * ncorrect / ntotal, 2),
    results=results,
)

EvaluationResult subclasses Prediction, which subclasses Example.
In the structure above, results has the type signature list[tuple["dspy.Example", "dspy.Example", Any]].
This is how we get an Example with, eventually, tuples that include Examples within them.

If this doesn't make sense, I can generate a minimal example, but the thing that failed for me is cherry-picking the save_as_json logic implemented in Example.__call__ in the current main (here)