dealing with missing values

[giacomociti]

hello,
I'm also trying to use eye-reasoner as a better SPARQL, but I'm struggling to find a way to express something akin to:

PREFIX : <http://example.com/>

CONSTRUCT {
  ?object :TitleWithoutType ?title
}
WHERE {
  ?object :Title ?title .
  OPTIONAL { ?title :Type ?type }
  FILTER (!BOUND(?type))
}

Thanks for your help

[josd]

The following should work

@prefix log: <http://www.w3.org/2000/10/swap/log#>.
@prefix : <http://example.com/>.

{
    {
        ?object :Title ?title.
    } log:callWithOptional {
        ?title :Type ?type.
    }.
    ?type log:bound false.
} => {
    ?object :TitleWithoutType ?title.
}.

Remark that we are still discussing those log: built-ins in the N3 community group.

Related to this, there is currently a lot of work going on in https://github.com/doerthe/SPARQL-to-N3

[giacomociti]

Thanks a lot, that's exactly what I was looking for

[josd]

$ cat g1.ttl
PREFIX : <http://example.com/>

:object1 :Title :title1.
:title1 :Type :type1.
:object2 :Title :title2.
:object3 :Title :title3.
:title3 :Type :type3.

$ cat g1.rq
PREFIX : <http://example.com/>

CONSTRUCT {
  ?object :TitleWithoutType ?title
}
WHERE {
    ?object :Title ?title .
    OPTIONAL { ?title :Type ?type }
    FILTER (!BOUND(?type))
}

$ arq --data=g1.ttl --query=g1.rq
@prefix : <http://example.com/> .

:object2  :TitleWithoutType  :title2 .

$ cat g1.n3
@prefix log: <http://www.w3.org/2000/10/swap/log#>.
@prefix : <http://example.com/>.

{
    {
        ?object :Title ?title.
    } log:callWithOptional {
        ?title :Type ?type.
    }.
    ?type log:bound false.
} => {
    ?object :TitleWithoutType ?title.
}.

$ eye --quiet --nope g1.ttl --query g1.n3
@prefix : <http://example.com/>.
@prefix log: <http://www.w3.org/2000/10/swap/log#>.

:object2 :TitleWithoutType :title2.