[Json] About JSON equality

[Francis Galiegue <[e-mail]>]

The subject has been brought, even though somewhat indirectly, in
another thread on this list, so here I will give a digest of what JSON
Schema came up with.

The definition of JSON value equality, as defined by the core
specification, is as such (link:
http://tools.ietf.org/html/draft-zyp-json-schema-04#section-3.6):

----
Two JSON values are said to be equal if and only if:

      both are nulls; or

      both are booleans, and have the same value; or

      both are strings, and have the same value; or

      both are numbers, and have the same mathematical value; or

      both are arrays, and:

         have the same number of items; and

         items at the same index are equal according to this definition;
         or

      both are objects, and:

         have the same set of property names; and

         values for a same property name are equal according to this
         definition.
----

This definition is only lacking for strings. On some other draft which
I cannot remember off the top of my head, two JSON String values are
to be considered equal if, position wise, their Unicode code points
are the same (and THAT INCLUDES \u0000).

Now, what is the value of defining equality of two JSON values in the
general case (see also my mail about why having to restrict JSON
representations to container instances)?

Of course, there is also the problem that for numeric instances, some
programming languages/parsers cannot guarantee that, since they cannot
reliably represent said instances in a reliable manner, but then this
is why the validation spec explicitly mentions this:
http://tools.ietf.org/html/draft-fge-json-schema-validation-00#section-3.2

About strings and the famous "zero character", this same specification
also says: http://tools.ietf.org/html/draft-fge-json-schema-validation-00#section-3.1

Yes, nothing forbids "\u0000" in a JSON string.

All this to say, should an equality definition find its place in a
potentially revised JSON RFC? Personally, I'm not so sure...

--
Francis Galiegue, [e-mail]
Try out your JSON Schemas: http://json-schema-validator.herokuapp.com