[PaulHoule]

I came to the conclusion that a List<X> is a good generic data structure, for instance in cases where the cardinality is supposed to be 0..1 it is often less trouble than a nullable scalar or an Optional<X> and you have cases where you’re going to get a list anyway such as if you are querying a relational database. (Often people write awkward code to turn that result into a nullable/Optional and then more awkward code to turn it back to a list later) Lists work almost exactly the same in most languages whereas there is often something weird about null, there might not be Optional, it might have something weird about it, etc.

For multi-language distributed processing, particular if JSON is involved it’s worth a try.

To be fair I write a lot of Java where Optional is a train wreck in so many ways not least it could be null anyway, you are allocating objects needlessly, and I just see people get hypnotized by awkward code also they write bugs or scan right past them.

[instig007]

yes, exactly, not sure why your comment was downvoted. Also, generally it's not cardinality of 0..1, it is `[]` vs `xs:[]`, that is - either empty, or a multitude of values, where 1 is a specific instance of the multitude (singleton).