UnionRepresentation

UnionRepresentation is a complete, inspectable union wire representation. For a format not covered by a ready-made value in UnionRepresentations, construct one directly:

UnionRepresentation.Internal("kind")
UnionRepresentation.Adjacent("kind", "fields", UnionPayloadStyle.Named)
UnionRepresentation.External(UnionPayloadStyle.Named, true)

• Internal tagField writes an internal tag inside the payload object, with named fields.
• Adjacent (tagField, payloadField, payloadStyle) writes the tag beside a single payload member holding the fields.
• External (payloadStyle, unwrapFieldless) writes a single-property object keyed by the case tag; unwrapFieldless encodes fieldless cases as bare strings.

Adjacent and external formats accept every UnionPayloadStyle. See UnionPayloadStyle for how each style shapes the payload, and Advanced Union Handling for the JSON each combination produces.