;;;  *** File not complete. Hacked to use 3.9 chez ***
;;;                             expd.s                               4/9/91
;;; C. David Boyer
;;;
;;; This file implements an expander for Chez Scheme. The only difference
;;; between this file and macrop.ss is that expand is not implemented.
;;; The file macros.ss should be loaded.
;;;

;;; (install-expander name function) ==> #unspecified
;(define install-expander
;  (lambda (name expander)
;    (if (symbol? name)
;	(putprop name '*scheme*macro* expander)
;	(error 'install-expander 
;	       "Invalid Name or Function: ~s ~s" name expander))))

(define remove-expander
  (lambda (name)
    (remprop name '*scheme*macro*)))

(define expand-top expand)
;  (lambda (e)
;    (if (and (pair? e) (symbol? (car e)))
;	(let ((macro-expander (getprop (car e) '*scheme*macro*)))
;	  (if macro-expander
;	      (macro-expander e)
;	      e))
;	e)))

(define expander?
  (lambda (x)
    (and (symbol? x)
	 (getprop x '*expander*))))          ;*scheme*macro*))))

(define get-expander
  (lambda (e)                ;*scheme*macro*)))
    (lambda (x y) ((getprop e '*expander*) x (lambda (x y) x)))))