gui.ss
(module gui mzscheme
  (require (planet "gui.ss" ("robby" "redex.plt" 3 9))
           (lib "etc.ss")
           "front-end.ss")

  (define graph
    (opt-lambda (semantics x [cutoff +inf.0])
      (parameterize ([reduction-steps-cutoff cutoff])
        (traces (semantics-language semantics)
                (semantics-reduction-relation semantics)
                (type-check semantics x)))))

  (define (step semantics x)
    (stepper (semantics-language semantics)
             (semantics-reduction-relation semantics)
             (type-check semantics x)))

  (provide graph step))