Should we support lists of lists?

[lanthaler]

Currently we do not support lists of lists since Gregg got into some problems in trying to make them work algorithmically and didn't have a real use case.

We should discuss whether we would like to support that or not and what happens if someone uses that feature nevertheless.

[msporny]

We need somebody to do a deep dive into this issue. I don't have a strong opinion one way or the other. It seems like something that would be easy to express using the syntax that we have, but may have severe complications when normalizing or converting to RDF.

@dlongley Do you have any thoughts on this?

[dlongley]

I recommend we make lists of lists illegal for the time being. We might support them in the future, but I don't see the need right now -- and don't think we should go making implementations more complicated for a use case that might be really limited.

[lanthaler]

That would be fine for me, we just have to make that clear in the spec. I think sooner or later we will need to add something like a schema to the spec to formally describe which constructs are allowed and which aren't. We are discovering a lot of corner cases these days..

[lanthaler]

RESOLVED: Lists of lists are not allowed for JSON-LD 1.0. If a list of lists is detected, the JSON-LD processor MUST throw an exception.

[alpha-beta-soup]

There's a use case for lists of lists in GeoJSON-LD: geojson/geojson-ld#12 (all non-point, non-empty geometries cannot be represented).

[gkellogg]

Lists of lists are supported in the working group draft: https://w3.org/TR/JSON-LD11.

The community group, which this site is based on, handed off work to the working group some time ago.

There is a specific example for Geo-JSON in the spec.