gistfile1.scm

  ;; Remove role list from list of class options
  (set! class-opts (plist-remove-keys class-opts '(:roles)))

  ;; Evaluate list of roles in outer context
  (set! roles (eval-list roles (%macro-expansion-environment)))

  ;; Extend used slot and options lists by matching lists in used roles
  ;; Also remove roles that conflict with superclass roles
  (set! roles (map* (lambda (role-object)
                      (let ((role (assert-instance role-object <role>)))
                        (set! slots (append slots 
                                            (role-slots role)))
                        (set! class-opts (append class-opts 
                                                 (role-options role)))
                        role))
                    roles))
  
  ;; put evaluated list of roles back
  (set! class-opts (nconc `(:roles ',roles)
                          class-opts))