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authorBryan Newbold <bnewbold@robocracy.org>2017-02-20 00:05:25 -0800
committerBryan Newbold <bnewbold@robocracy.org>2017-02-20 00:05:25 -0800
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treea2be9aad5101c5e450ad141d15c514bc9c2a2963 /defmacex.scm
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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))