Re: Language Maps and default language

Ahh, yup.  The specification text isn't clear (IMHO) but the algorithm
definitely is.  We'll fall back to some pre-processing to add a language of
"" or "UND" before compaction.

Thanks Gregg, as always!

Rob

On Mon, Sep 19, 2016 at 2:07 PM, Gregg Kellogg <gregg@greggkellogg.net>
wrote:

> On Sep 19, 2016, at 11:38 AM, Robert Sanderson <azaroth42@gmail.com>
> wrote:
>
>
> Dear all,
>
> I'd love some clarification around the expected behavior of language maps
> with a default language.
>
> For example, in a context, one might use:
>   "label" : {"@id": "rdfs:label", "@container": "@language", "@language":
> "en"}
>
> I would expect this to then add a language of "en" to any string that does
> not have a language set.  And indeed this works in the playground:
>     http://tinyurl.com/zn9jxkz
>
> However, when loading the data from NQuads, this does not work:
>
> _:b0 <http://www.w3.org/2000/01/rdf-schema#label> "bar" .
> _:b0 <http://www.w3.org/2000/01/rdf-schema#label> "fish" .
>
> results in
>
> {'@context': {
>     'label': {'@container': '@language', '@id': 'rdfs:label', '@language':
> 'en'},
>     'rdfs': 'http://www.w3.org/2000/01/rdf-schema#'
>   },
>   '@id': '_:b0',
>   'rdfs:label': ['bar', 'fish']
> }
>
> rather than using the label key and assigning the default language of "en".
>
> I would expect, per the playground:
>
> {
>   "@context": {
>     "rdfs": "http://www.w3.org/2000/01/rdf-schema#",
>     "label": {"@id": "rdfs:label", "@container": "@language", "@language":
> "en"}
>   },
>   "label": {
>     "en": [ "fish", "bar" ]
>   }
> }
>
>
> Thanks in advance for any thoughts.
>
>
> Hi Rob, I agree that this is unintuitive, and is arguably a bug in the
> spec. (In general, IMHO, the spec is overly prescriptive in the algorithms,
> but some means of ensuring interoperability between implementations is
> necessary, and normative text that covers each permutation would be
> unwieldy; perhaps we can try better in a future CG version of the specs).
>
> In this case, the algorithm is correct; the NQuads defines “bar” and
> “fish” as having no language, whereas the context provides a default
> language. If you look at the Term Selection algorithm [1], you’ll see that
> if the literal values had a language, it would prefer to use a language
> map. Note that the @language definition in the term does affect
> transformation from NQuads to expanded JSON-LD, so the literals come across
> without language. If, instead, you had the following:
>
> _:b0 <http://www.w3.org/2000/01/rdf-schema#label> “bar”@en .
> _:b0 <http://www.w3.org/2000/01/rdf-schema#label> “fish”@en .
>
> You would get the language map back.
>
> The @language definition within the term would be useful when expanding
> JSON-LD where the string values were “foo” and “bar”; the context would say
> that these should be considered to have @language “en”, but that’s because
> the JSON-LD is in compact form.
>
> Gregg
>
> [1] http://www.w3.org/TR/json-ld-api/#term-selection
>
> Rob
>
> --
> Rob Sanderson
> Semantic Architect
> The Getty Trust
> Los Angeles, CA 90049
>
>
>


-- 
Rob Sanderson
Semantic Architect
The Getty Trust
Los Angeles, CA 90049