[PATCH] Preserve keyword in 'syntax-rules' and 'define-syntax-rule'

[Mark H Weaver]

Hello all,

I'd like to be able to do things like this:

--8<---------------cut here---------------start------------->8---
(define-syntax alt-environment
  (syntax-rules ()
    ((alt-environment)
     (the-environment alt-environment))))
--8<---------------cut here---------------end--------------->8---

and have it actually capture the lexical environment of the macro use.
Unfortunately, this doesn't work because the definitions of
'syntax-rules' and 'define-syntax-rule' discard the identifier of the
keyword.

Another possible use of the keyword identifier would be to pass it to
'datum->syntax' or 'syntax-locally-bound-identifiers'.

This patch fixes these problems.  Comments and suggestions solicited.

    Thanks,
      Mark

>From 3e3d32dd9b2d71ffb0703dedc4d47387e981c9b5 Mon Sep 17 00:00:00 2001
From: Mark H Weaver <address@hidden>
Date: Mon, 8 Oct 2012 14:08:43 -0400
Subject: [PATCH] Preserve keyword identifier in 'syntax-rules' and
 'define-syntax-rule'

* module/ice-9/psyntax-pp.scm (syntax-rule, define-syntax-rule):
  Preserve the keyword identifier.

* module/ice-9/psyntax-pp.scm: Regenerate.
---
 module/ice-9/psyntax-pp.scm |   24 ++++++++++++------------
 module/ice-9/psyntax.scm    |    8 ++++----
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/module/ice-9/psyntax-pp.scm b/module/ice-9/psyntax-pp.scm
index 68d1bf6..b148c9a 100644
--- a/module/ice-9/psyntax-pp.scm
+++ b/module/ice-9/psyntax-pp.scm
@@ -2551,12 +2551,13 @@
                            (cons '#(syntax-object syntax-case ((top)) (hygiene 
guile))
                                  (cons '#(syntax-object x ((top)) (hygiene 
guile))
                                        (cons k
-                                             (map (lambda (tmp-1 tmp)
-                                                    (list (cons 
'#(syntax-object dummy ((top)) (hygiene guile)) tmp)
+                                             (map (lambda (tmp-2 tmp-1 tmp)
+                                                    (list (cons tmp tmp-1)
                                                           (list 
'#(syntax-object syntax ((top)) (hygiene guile))
-                                                                tmp-1)))
+                                                                tmp-2)))
                                                   template
-                                                  pattern))))))
+                                                  pattern
+                                                  keyword))))))
                    tmp)
             (let ((tmp ($sc-dispatch tmp-1 '(_ each-any any . #(each ((any . 
any) any))))))
               (if (if tmp
@@ -2576,12 +2577,13 @@
                                (cons '#(syntax-object syntax-case ((top)) 
(hygiene guile))
                                      (cons '#(syntax-object x ((top)) (hygiene 
guile))
                                            (cons k
-                                                 (map (lambda (tmp-1 tmp)
-                                                        (list (cons 
'#(syntax-object dummy ((top)) (hygiene guile)) tmp)
+                                                 (map (lambda (tmp-2 tmp-1 tmp)
+                                                        (list (cons tmp tmp-1)
                                                               (list 
'#(syntax-object syntax ((top)) (hygiene guile))
-                                                                    tmp-1)))
+                                                                    tmp-2)))
                                                       template
-                                                      pattern))))))
+                                                      pattern
+                                                      keyword))))))
                        tmp)
                 (syntax-violation
                   #f
@@ -2601,8 +2603,7 @@
                            name
                            (list '#(syntax-object syntax-rules ((top)) 
(hygiene guile))
                                  '()
-                                 (list (cons '#(syntax-object _ ((top)) 
(hygiene guile)) pattern)
-                                       template))))
+                                 (list (cons name pattern) template))))
                    tmp)
             (let ((tmp ($sc-dispatch tmp-1 '(_ (any . any) any any))))
               (if (if tmp
@@ -2616,8 +2617,7 @@
                                (list '#(syntax-object syntax-rules ((top)) 
(hygiene guile))
                                      '()
                                      docstring
-                                     (list (cons '#(syntax-object _ ((top)) 
(hygiene guile)) pattern)
-                                           template))))
+                                     (list (cons name pattern) template))))
                        tmp)
                 (syntax-violation
                   #f
diff --git a/module/ice-9/psyntax.scm b/module/ice-9/psyntax.scm
index 6c264a6..dc32f5a 100644
--- a/module/ice-9/psyntax.scm
+++ b/module/ice-9/psyntax.scm
@@ -2789,7 +2789,7 @@
            #((macro-type . syntax-rules)
              (patterns pattern ...))
            (syntax-case x (k ...)
-             ((dummy . pattern) #'template)
+             ((keyword . pattern) #'template)
              ...)))
       ((_ (k ...) docstring ((keyword . pattern) template) ...)
        (string? (syntax->datum #'docstring))
@@ -2799,7 +2799,7 @@
            #((macro-type . syntax-rules)
              (patterns pattern ...))
            (syntax-case x (k ...)
-             ((dummy . pattern) #'template)
+             ((keyword . pattern) #'template)
              ...))))))
 
 (define-syntax define-syntax-rule
@@ -2808,13 +2808,13 @@
       ((_ (name . pattern) template)
        #'(define-syntax name
            (syntax-rules ()
-             ((_ . pattern) template))))
+             ((name . pattern) template))))
       ((_ (name . pattern) docstring template)
        (string? (syntax->datum #'docstring))
        #'(define-syntax name
            (syntax-rules ()
              docstring
-             ((_ . pattern) template)))))))
+             ((name . pattern) template)))))))
 
 (define-syntax let*
   (lambda (x)
-- 
1.7.10.4