% From The Art of Eyepl, Chapter 11.
why(
  type(socrates, mortal),
  proof(
    goal(type(socrates, mortal)),
    by(rule("socrates.pl", clause(4))),
    bindings([binding("X", socrates)]),
    uses([
      proof(
        goal(type(socrates, man)),
        by(fact("socrates.pl", clause(3)))
      )
    ])
  )
).