q:select with list only graph

given

@prefix ex: <http://example.org/ex#>.
ex:Joe a ex:Librarian; ex:hairColor "black".
ex:Mary a ex:Librarian; ex:hairColor "red".

I would expect that cwm --query

@prefix ex: <http://example.org/ex#>.
@prefix q: <http://www.w3.org/2004/ql#>.
[] q:select { (?x ?y) };
   q:where { ?x a ex:Librarian; ex:hairColor ?y }.

returns

     @prefix : <http://example.org/eg#> .
     @prefix ex: <http://example.org/ex#> .
 
      ( ex:Joe 
        "black"  ) .
      ( ex:Mary 
        "red"  ) .

but we actually get an empty graph...

-- 
Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/