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Precedence of @vocab

From: Niklas Lindström <lindstream@gmail.com>
Date: Fri, 29 Mar 2013 18:33:22 +0100
Message-ID: <CADjV5je+VS6wi_t0g640XvVOcMZ7T5YX6MZTnYov9xxUJmn1yw@mail.gmail.com>
To: public-linked-json@w3.org
Hi all,

I'd like to verify that `@vocab`, when used in compaction, takes
precedence over any prefix with the same value. For instance, I'd
expect that this data:

    {
      "@type": "http://schema.org/Document",
      "http://schema.org/name": "Something"
    }

when compacted with this context:

    {
      "@context": {
        "schema": "http://schema.org/",
        "@vocab": "http://schema.org/"
      }
    }

results in:

    {
      "@type": "Document",
      "name": "Something"
    }

I believe that compaction is specified like this, according to in "8.3
IRI Compaction" [1]:

> we first try to find a term that the IRI or keyword can be compacted to if it is relative to active context's vocabulary mapping.

But in both the official and Markus' playground, the results uses
"schema:Document" and "schema:name".

.. Of course, in the above example, just removing the "schema" term
would do the trick. But in practice, it is often useful to both set a
default vocabulary and also have a prefix for the same IRI, in order
to e.g. rename certain terms (and relying on prefixes to shorten the
context size). E.g. to make plural forms of terms with a `@container`
of `@set` or `@list, like:

        "contributors": {"@id": "schema:contributor", "@container": "@set"},
        ...

(Or for specific datatyped values, or terms with predefined language, etc.)

Moreover, sometimes you want to have a list of contexts, the first
defining common prefixes and the latter declaring your specific
context needs. While you can end by setting a `@vocab` and then
setting any prefix with that same value to `null`, that can be brittle
and cumbersome.

Cheers,
Niklas

[1]: http://json-ld.org/spec/latest/json-ld-api/#iri-compaction
Received on Friday, 29 March 2013 17:34:19 UTC

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