virtual construct

[justin2004]

hey @cmungall ,

continuing our discussion from here:
#1

i recently came across "SPARQL magic properties."

"A computed property (also known as property functions or magic properties) is a predicate that occurs in a SPARQL query pattern with matching semantics other than simple subgraph matching."
https://www.w3.org/wiki/SPARQL/Extensions/Computed_Properties

and this feels like a way to increase composability without relying on inference or materalization.

franz has a good example of this here:
https://franz.com/agraph/support/documentation/current/magic-properties.html#Generators

they basically make the property ex:coCreators expand into the specified SPARQL select.

insert data {  
  graph sna:sna {  
   [ a sna:Generator ;  
       sna:hasName ex:coCreators ;  
       sna:hasSPARQL '''  
prefix dc: <http://purl.org/dc/elements/1.1/>  
select distinct ?output {  
  ?article dc:creator ?input .  
  ?article dc:creator ?output .  
  FILTER( ?input != ?output )  
}''' ]  
  }  
} 

that is a binary predicate but there also might be room to define higher arity predicates (like you do in sparqlprog):

select * {  
  ?book fti:match ('willows' 'titles' ) .  
}