I'm sceptical about the value proposition of this without seeing much more than a simple example that offers little over existing hypermedia+json/csv practices.

If a compact columnar representation is what you're after to avoid having to repeat every field name in an array of objects (which CSV is good for) but you don't want to give up the ability to include metadata in your JSON, there are a ton of different ways for structure your document to solve this issue without inventing new document formats.

Also this example is unclear (possibly ambiguous?); how is "int" as a type for the "age" column distinguished from "street", "city", etc as what I assume are field names?

> If a compact columnar representation is what you're after to avoid having to repeat every field name in an array of objects (which CSV is good for)

Plus, as I wrote elsewhere, gzipping your JSON will result in essentially "avoiding having to repeat every field name" by dictionary coding it. The only case in which that wouldn't be true is when dealing with extremely unusual and heteromorphic data, but then this format doesn't seem to support such data at all.

I'm also mystified that the author claims this is readable. It looks eminently unreadable compared with JSON, if you have anything beyond one row of very simple data with all optional fields present. And, in that case, it's basically just 'JSON with the keys on a different row'.

(Congrats to the author, but this is more of a fun personal project rather than something to seriously present as a 'JSON killer'. If you do present it as a JSON killer, then you have to expect a rigorous review.)

> Plus, as I wrote elsewhere, gzipping your JSON will result in essentially "avoiding having to repeat every field name" by dictionary coding it.

Gzipping indeed helps in getting mostly back the space taken by the field names, but a parser will still have to parse these strings. On a large document, this might have a performance impact.

One good side of having the field names however is that one can reorder them adlib.

If your worry is parsing speed, then JSON not only has battle-tested parsers, but also has SIMD-assisted parsers which can process gigabytes a second on a single core (e.g. https://github.com/simdjson/simdjson). It would take Internet Object years to develop parsers as performant as that, even if it did, by some miracle, achieve wide uptake. So the notional advantage afforded by not having keys on each row is neither here nor there.

And incidentally, as someone who's written a handful of parsers, I suspect that this scheme would not be particularly easy to parse. You need lookahead because of optional fields, as well as maintaining state and a lookup table for mapping positions to keys, etc. I can draw up a quick parser in pseudocode or Python to explain, if you disagree.