HXQ-0.5: data/q1.xq

define function f ( $x, $y ) = <student>{$x,' ',$y}</student>;

<students>{
    for $s in doc('data/cs.xml')//gradstudent
    order by $s/gpa descending, $s//lastname
    return f( $s/name, $s/gpa/text() )
}</students>