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https://issues.apache.org/jira/browse/JENA-1313?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15953465#comment-15953465
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Andy Seaborne commented on JENA-1313:
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{{collate:collate(?label, 'fi')}} has one varying argument for the data to be
sorted. The {'fi'}} is fixed (it's really naming a subcase of
{{collate:collate}} - more like {{collate:collate<'fi'>(?label)}}.
It's a curried function on the second argument, right?:-)
I have no idea how {{collate:collate(?value, ?lang)}} would work except it is
almost certain to have instability problems comparing across languages in a
single sort. See my example in [the message of Oct 25,
2016|http://markmail.org/message/ig4w7wqkxsssgqdt]. Java "sort" can throw an
exception because the comparator contract is broken.
Yes - it's a corner case. The sort of thing that causes users@ questions!
A comparator needs to be {{compare(?value1, ?value2, fixed)}} - two values from
the data.
> Language-specific collation in ARQ
> ----------------------------------
>
> Key: JENA-1313
> URL: https://issues.apache.org/jira/browse/JENA-1313
> Project: Apache Jena
> Issue Type: Improvement
> Components: ARQ
> Affects Versions: Jena 3.2.0
> Reporter: Osma Suominen
>
> As [discussed|http://markmail.org/message/v2bvsnsza5ksl2cv] on the users
> mailing list in October 2016, I would like to change ARQ collation of literal
> values to be language-aware and respect language-specific collation rules.
> This would probably involve changing at least the
> [NodeUtils.compareLiteralsBySyntax|https://github.com/apache/jena/blob/master/jena-arq/src/main/java/org/apache/jena/sparql/util/NodeUtils.java#L199]
> method.
> It currently sorts by lexical value first, then by language tag. Since the
> collation order needs to be stable across all possible literal values, I
> think the safest way would be to sort by language tag first, then by lexical
> value according to the collation rules for that language.
> But what about subtags like {{@en-US}} or {{@pt-BR}}? Can they have different
> collation rules than the main language? It would be a bit strange if all
> {{@en-US}} literals sorted after {{@en}} literals...
> It would be good to check how Dydra does this and possibly take the same
> approach. See the message linked above for further backgound.
> I've been talking with [~kinow] about this and he may be interested in
> implementing it.
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