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;;;"defmacex.scm" defmacro:expand* for any Scheme dialect.
;;;Copyright 1993-1994 Dorai Sitaram and Aubrey Jaffer.
;
;Permission to copy this software, to redistribute it, and to use it
;for any purpose is granted, subject to the following restrictions and
;understandings.
;
;1. Any copy made of this software must include this copyright notice
;in full.
;
;2. I have made no warrantee or representation that the operation of
;this software will be error-free, and I am under no obligation to
;provide any services, by way of maintenance, update, or otherwise.
;
;3. In conjunction with products arising from the use of this
;material, there shall be no use of my name in any advertising,
;promotional, or sales literature without prior written consent in
;each case.
;;;expand thoroughly, not just topmost expression. While expanding
;;;subexpressions, the primitive forms quote, lambda, set!, let/*/rec,
;;;cond, case, do, quasiquote: need to be destructured properly. (if,
;;;and, or, begin: don't need special treatment.)
(define (defmacro:iqq e depth)
(letrec
((map1 (lambda (f x)
(if (pair? x) (cons (f (car x)) (map1 f (cdr x)))
x)))
(iqq (lambda (e depth)
(if (pair? e)
(case (car e)
((quasiquote) (list (car e) (iqq (cadr e) (+ 1 depth))))
((unquote unquote-splicing)
(list (car e) (if (= 1 depth)
(defmacro:expand* (cadr e))
(iqq (cadr e) (+ -1 depth)))))
(else (map1 (lambda (e) (iqq e depth)) e)))
e))))
(iqq e depth)))
(define (defmacro:expand* e)
(if (pair? e)
(let* ((c (macroexpand-1 e)))
(if (not (eq? e c))
(defmacro:expand* c)
(case (car e)
((quote) e)
((quasiquote) (defmacro:iqq e 0))
((lambda define set!)
(cons (car e) (cons (cadr e) (map defmacro:expand* (cddr e)))))
((let)
(let ((b (cadr e)))
(if (symbol? b) ;named let
`(let ,b
,(map (lambda (vv)
`(,(car vv)
,(defmacro:expand* (cadr vv))))
(caddr e))
,@(map defmacro:expand*
(cdddr e)))
`(let
,(map (lambda (vv)
`(,(car vv)
,(defmacro:expand* (cadr vv))))
b)
,@(map defmacro:expand*
(cddr e))))))
((let* letrec)
`(,(car e) ,(map (lambda (vv)
`(,(car vv)
,(defmacro:expand* (cadr vv))))
(cadr e))
,@(map defmacro:expand* (cddr e))))
((cond)
`(cond
,@(map (lambda (c)
(map defmacro:expand* c))
(cdr e))))
((case)
`(case ,(defmacro:expand* (cadr e))
,@(map (lambda (c)
`(,(car c)
,@(map defmacro:expand* (cdr c))))
(cddr e))))
((do)
`(do ,(map
(lambda (initsteps)
`(,(car initsteps)
,@(map defmacro:expand*
(cdr initsteps))))
(cadr e))
,(map defmacro:expand* (caddr e))
,@(map defmacro:expand* (cdddr e))))
(else (map defmacro:expand* e)))))
e))
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