PLT Scheme: Converting one of the macros in 'Casting SPELs in LISP'

    (defspel game-action (command subj obj place &rest rest)
  `(defspel ,command (subject object)
     `(cond ((and (eq *location* ',',place)
                  (eq ',subject ',',subj)
                  (eq ',object ',',obj)
                  (have ',开发者_如何学Python',subj))
             ,@',rest)
            (t '(i cant ,',command like that.)))))

Thats the code from http://www.lisperati.com/actions.html for the 'macro defining macro'. I can't seem to convert it appropriately to scheme. Can someone explain to me the process of creating this same sort of thing in Scheme?

This kind of macro is actually much simpler in Scheme, since you can do it all with define-syntax-rule (in standard Scheme code you will need define-syntax + syntax-rules). You basically do the same thing, minus the whole quote/unquote mess.

(defspel (game-action command subj obj place rest ...)
  (defspel (command subject object)
    (cond [(and (eq? *location* 'place)
                (eq? 'subject 'subj)
                (eq? 'object 'obj)
                (have 'subj))
           rest ...]
          [else '(i cant command like that.)])))

And since this is actually most of the code, I ported the whole thing to PLT -- see the post on the mailing list.