PREFIX      :    <http://example/> 
PREFIX  xsd:    <http://www.w3.org/2001/XMLSchema#>
PREFIX  rdf:    <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX  apf:    <java:com.hp.hpl.jena.query.pfunction.library.>
PREFIX  arq:    <http://jena.hpl.hp.com/ARQ#>

SELECT *
{
    xsd:string arq:splitIRI (?a ?b) .

    :foo apf:splitURI (?x "foo") .
    :fooY apf:splitURI (: ?y) .
    :foo apf:splitURI ("http://example/" "foo") .
}