Re: Yayson (proposal for a YAML presentation embedded within JSON for browser clients)

On Tue, Jun 8, 2010 at 3:05 PM, Matthew Willson
<[email protected]>wrote:

> > Have you seen the JSYNC proposal I made last month? http://www.jsync.org
>
> Aha, yeah that's exactly what I wanted! and a more concise syntax than
> mine.
>
> I did google for something along these lines ("yaml inside json", etc) but
> nothing showed up, apologies for the dup :)
>
> > I think it covers what you are trying to accomplish here, and even
> resolves your caveats. It provides everything that you can do in YAML, using
> standard JSON encoding.
>
> Great!
>
> There's a few cases which the webpage doesn't include in its examples:
>

That page was just to give a rough idea of what was going on. I didn't want
to scare people away with all the niggly details, on first glimpse. When I
write the spec, it will cover everything.

I've figured out all the edge cases, though. There's not really much to it,
syntax-wise. But implementing it won't be trivial. We have to do tag
resolution, implicit and explicit, prewalk to detect duplicate refs on
dumps, provide a nice API for custom tagging etc. Monkey-hacking this into
existing implementations will be interesting.

Still, I think it is all very doable. I want to be sure to provide a nice
and consistent API across all implementations. ie There needs to be an API
spec, as well. I think that's one area where YAML has fallen down. I think
if JSYNC is a success, then the API can be retrofitted to YAML
implementations.

I'll address your points below...

* A tagged custom type which is constructed from (say) a string rather than
> from a map - my example was {"$tag": "!!timestamp",  "$value":
> "2001-12-15T02:59:43.1Z"}
>

"!!timestamp 2001-12-15T02:59:43.1Z"


> * An anchor attached to a string/array/some non-map type - my example was
> {"$anchor": "foo", "$value": "some string"}
>

[ "&anchor1", "x", "y", "&anchor2 z"]

--- &anchor1
- x
- y
- &anchor2 z


> * Use of one of the special reserved keys "!" or "&" as a normal key of a
> mapping (would need to be escaped somehow)
>

{
   ".!oh": "my!",
   ".&gt;": ">"
}

---
'!oh': my!
'&gt': '>'

* A map with non-string keys
>

{"!!int 4": "four"}

---
4: four


> * A string value which starts with "*" which you don't want treated as a
> reference
>

[".*anchor"]

---
- '*anchor'


> On that last point, perhaps it would be easier to do references as {"*":
> "001"} rather than "*001". That means that you then only need to reserve one
> other map key, "*", rather than have to reserve (and escape normal uses of)
> all strings starting with *, noting that this requires every string value to
> be checked when mapping a parsed JSON tree to a YAML graph.
>

I think that too complicated visually. You need to check every string node
anyway, to see if it has a type or anchor, so no real penalty doing "*001".


> > Want to help me with it?
>
> Sure - see the above :)
>

Great. Join #jsync on irc.freenode.net if you do IRC.


> I guess the ultimate awkward corner case would be:
>
> A tagged custom type, which is also given an anchor, and which is created
> from a map with some non-string keys and some (suitably-escaped) reserved
> keys.
>

{
   "!": "custom",
   "&": "anchor",
   "!!int 55": "I can't drive",
   "awesome": ".!!!"
}

--- !custom &anchor
55: I can't drive
awesome: '!!!'

Any thoughts on a media type for this? eg application/yaml+json ?
>

application/jsync ?


> Also, I guess an alternative approach (or perhaps one which is undertaken
> in parallel?) would be to propose an extension to json with new syntax for
> references and tags, to match the YAML model, but only the minimal extra
> syntax required to do so, with the goal of keeping it as easy to parse as
> possible.
>

Explain this more. I don't really see what you are proposing...

Cheers, Ingy


> -Matt

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