New function: macroexpand-match.

* stdlib/match.tl (macroexpand-match): New function.

* autoload.c (match_set_entries): Autoload match
module on macroexpand-match.

* txr.1: Documented.

* stdlib/doc-syms.tl: Updated.

4 files changed, 57 insertions, 0 deletions

diff --git a/autoload.c b/autoload.c
index 336c2518..e266ed43 100644
--- a/autoload.c
+++ b/autoload.c
@@ -826,6 +826,7 @@ static val match_set_entries(val fun)
     lit("match"), lit("match-ecase"),
     lit("while-match"), lit("while-match-case"), lit("while-true-match-case"),
     lit("lambda-match"), lit("defun-match"), lit("defmatch"),
+    lit("macroexpand-match"),
     lit("each-match"), lit("append-matches"),
     lit("keep-matches"), lit("each-match-product"),
     lit("append-match-products"), lit("keep-match-products"),
diff --git a/stdlib/doc-syms.tl b/stdlib/doc-syms.tl
index e75ad2c7..2b0edcaf 100644
--- a/stdlib/doc-syms.tl
+++ b/stdlib/doc-syms.tl
@@ -1187,6 +1187,7 @@
       ("macroexpand-1-lisp1" "N-01E62179")
       ("macroexpand-1-place" "N-00684FF9")
       ("macroexpand-lisp1" "N-01E62179")
+      ("macroexpand-match" "N-02CCCB67")
       ("macroexpand-params" "N-037EB49A")
       ("macroexpand-place" "N-00684FF9")
       ("macrolet" "N-00AC12C0")
diff --git a/stdlib/match.tl b/stdlib/match.tl
index 55d50417..ff3134fd 100644
--- a/stdlib/match.tl
+++ b/stdlib/match.tl
@@ -833,6 +833,11 @@
                                      ,args ,*body)))
        ',name)))
 
+(defun macroexpand-match (pattern : env)
+  (iflet ((xfun (and (consp pattern) [*match-macro* (car pattern)])))
+    [xfun pattern env]
+    pattern))
+
 (defun check (f op pat)
   (if (or (not (listp pat))
           (meq (car pat) 'sys:expr 'sys:var 'sys:quasi))
diff --git a/txr.1 b/txr.1
index 9a3578b3..4c2ee369 100644
--- a/txr.1
+++ b/txr.1
@@ -46939,6 +46939,56 @@ environment.
   -> nil
 .brev
 
+.coNP Function @ macroexpand-match
+.synb
+.mets (macroexpand-match < pattern <> [ env ])
+.syne
+.desc
+If
+.code pattern
+is a compound form whose operator symbol has been defined as a macro
+pattern using
+.codn defmatch ,
+then
+.code macroexpand-match
+will expand that pattern and return the expansion. Otherwise it returns the
+.code pattern
+argument.
+
+In order to be recognized by
+.code macroexpand-match
+the
+.meta pattern
+argument must not include the
+.code @
+prefix that would normally be used to invoke it. The expansion, however, will
+include that syntax.
+
+The
+.code env
+parameter specifies the macro-time environment for the expander.
+Note: pattern expanders, like built-in patterns, may use the macro environment
+for deciding whether a variable is an existing lexical variable, or a free
+variable, based on which a pattern may be expanded differently.
+
+.TP* Example:
+
+Given:
+.verb
+  (defmatch point (x y)
+    ^@(struct point x @,x y @,y))
+.brev
+a result similar to the following may be obtained:
+.verb
+  (macroexpand-match '(point a b)) -> @(struct point x @a y @b)
+.brev
+Note that the pattern is specified plainly as
+.code "(point a b)"
+rather than
+.codn "@(point a b)" ,
+yet the expansion is
+.codn "@(struct ...)" .
+
 .coNP Special variable @ *match-macro*
 .desc
 The