Alright, I found my solution, I used kotlinx.seria...

# arrow

[kluck]

Alright, I found my solution, I used kotlinx.serialization for my purposes with this class:

@Serializer(forClass = Option::class)
class OptionSerializer<T : Any>(private val dataSerializer: KSerializer<T>) : KSerializer<Option<T>> {
    override val descriptor: SerialDescriptor = StringDescriptor.withName("OptionDescriptor")

    override fun deserialize(input: Decoder): Option<T> {
        return Option.fromNullable(input.decodeNullable(dataSerializer))
    }

    override fun serialize(output: Encoder, obj: Option<T>) {
        when (obj) {
            is None -> output.encodeNull()
            is Some -> output.encodeNullable(dataSerializer, obj.t)
        }
    }
}

Then, I need to annotate my class @Serializable data class Stuff(@Serializable(with = OptionSerializer::class) val foo: Option<String>)
The downside is the verbosity, as the Option class is not annotated with @Serializable, I have to add this chunk @Serializable(with = OptionSerializer::class) to every optional property.

Here's a simple test and it's output: