From: Doug Evans <xdje42@gmail.com>
Date: Mon, 20 Jul 2009 00:57:03 +0000 (+0000)
Subject: 	Fix binding of nested pmacro parameters.
X-Git-Url: https://sourceware.org/git/?a=commitdiff_plain;h=341ed0361d3767bbc1ffea6da0e64f660ac8652b;p=cgen.git

	Fix binding of nested pmacro parameters.
	* pmacros.scm (-pmacro-env-make): New arg prev-env.
	All callers updated.
	(-pmacro-bulid-lambda): Ditto.
	* doc/pmacros.texi: Update.
---

diff --git a/ChangeLog b/ChangeLog
index 478d037..40dfe3a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2009-07-19  Doug Evans  <dje@sebabeach.org>
 
+	Fix binding of nested pmacro parameters.
+	* pmacros.scm (-pmacro-env-make): New arg prev-env.
+	All callers updated.
+	(-pmacro-bulid-lambda): Ditto.
+	* doc/pmacros.texi: Update.
+
 	* ifield.scm (-multi-ifield-make-default-insert): Fix shifts
 	calculation.
 	(-multi-ifield-make-default-extract): Ditto.
diff --git a/doc/pmacros.texi b/doc/pmacros.texi
index 710c4c5..3b25203 100644
--- a/doc/pmacros.texi
+++ b/doc/pmacros.texi
@@ -859,14 +859,13 @@ Example:
 (load-op uh OP2_11 HI (.pmacro (mode expr) (zext mode expr)))
 @end smallexample
 
-.pmacro's don't bind the way Scheme lambda expressions do.
-In the following example, arg2 in the second pmacro is not bound
-to the arg2 argument of the first pmacro.
-@c FIXME: Feels like a bug rather than a feechure.
+.pmacro's bind the same way Scheme lambda expressions do.
+In the following example, arg2 in the second pmacro is bound
+to the arg2 argument of the outer pmacro.
 
 @smallexample
 (define-pmacro (foo arg1 arg2) ((.pmacro (bar) (+ arg2 bar)) arg1))
-(foo 3 4) ==> (+ arg2 3)
+(foo 3 4) ==> (+ 4 3)
 @end smallexample
 
 @node Passing macros as arguments
diff --git a/pmacros.scm b/pmacros.scm
index b56fcb5..922149b 100644
--- a/pmacros.scm
+++ b/pmacros.scm
@@ -100,9 +100,7 @@
 ; .sym and .str convert numbers to symbols/strings as necessary (base 10).
 ;
 ; .pmacro is for constructing pmacros on-the-fly, like lambda, and is currently
-; only valid as arguments to other macros.
-; ??? Nested pmacros don't bind their arguments the way nested lambda's do.
-; Should they?
+; only valid as arguments to other macros or assigned to a local in a {.let}.
 ;
 ; ??? Methinks .foo isn't a valid R5RS symbol.  May need to change 
 ; to something else.
@@ -142,7 +140,9 @@
 ; Cover functions to manage an "environment" in case a need or desire for
 ; another method arises.
 
-(define (-pmacro-env-make names values) (map cons names values))
+(define (-pmacro-env-make prev-env names values)
+  (append! (map cons names values) prev-env)
+)
 (define (-pmacro-env-ref env name) (assq name env))
 
 ; Error message generator.
@@ -437,10 +437,11 @@
 
 ; Build a procedure that performs a pmacro expansion.
 
-(define (-pmacro-build-lambda params expansion)
+(define (-pmacro-build-lambda prev-env params expansion)
   (eval1 `(lambda ,params
 	    (-pmacro-expand ',expansion
-			    (-pmacro-env-make ',params (list ,@params)))))
+			    (-pmacro-env-make ',prev-env
+					      ',params (list ,@params)))))
 )
 
 ; ??? I'd prefer to use `define-macro', but boot-9.scm uses it and
@@ -458,7 +459,7 @@
 ; name).
 ; ??? The goal here is to follow Scheme's define/lambda, but not all variants
 ; are supported yet.  There's also the difference that we treat undefined
-; symbols as being themselves.
+; symbols as being themselves (i.e. "self quoting" so-to-speak).
 ;
 ; ??? We may want user-definable "syntactic" macros some day.  Later.
 
@@ -490,7 +491,8 @@
 	    (-pmacro-set! name (-pmacro-make name #f #f #f expansion comment)))
 	(-pmacro-set! name
 		      (-pmacro-make name arg-spec default-values #f
-				    (-pmacro-build-lambda arg-spec expansion)
+				    (-pmacro-build-lambda nil
+							  arg-spec expansion)
 				    comment))))
     *UNSPECIFIED*
 )
@@ -715,7 +717,8 @@
   ;; e.g. (define (foo bar . baz) ...)
   (if (not (list? params))
       (-pmacro-error ".pmacro parameter-spec is not a list" params))
-  (-pmacro-make '.anonymous params #f #f (-pmacro-build-lambda params expansion) "")
+  (-pmacro-make '.anonymous params #f #f
+		(-pmacro-build-lambda env params expansion) "")
 )
 
 ; (.let (var-list) expr1 . expr-rest)