From 5e1226c161ac4dd114fa5071baa943f72b79741c Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sun, 12 Mar 2017 10:30:56 -0700
Subject: match-fun: make last two args optional.

* eval.c (eval_init): Update registration of match-fun.

* match.c (match_fun): Do defaulting on third and fourth arg.

* txr.1: Documenation updated.
---
 eval.c  |  2 +-
 match.c |  4 +++-
 txr.1   | 11 +++++++----
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/eval.c b/eval.c
index 40847c40..f5895520 100644
--- a/eval.c
+++ b/eval.c
@@ -6079,7 +6079,7 @@ void eval_init(void)
   reg_fun(intern(lit("return*"), user_package), func_n2o(return_star, 1));
   reg_fun(intern(lit("abscond*"), system_package), func_n2o(abscond_star, 1));
 
-  reg_fun(intern(lit("match-fun"), user_package), func_n4(match_fun));
+  reg_fun(intern(lit("match-fun"), user_package), func_n4o(match_fun, 2));
 
   reg_fun(intern(lit("time"), user_package), func_n0(time_sec));
   reg_fun(intern(lit("time-usec"), user_package), func_n0(time_sec_usec));
diff --git a/match.c b/match.c
index 63cd572a..1283bd73 100644
--- a/match.c
+++ b/match.c
@@ -4557,10 +4557,12 @@ val match_filter(val name, val arg, val other_args)
   }
 }
 
-val match_fun(val name, val args, val input, val files)
+val match_fun(val name, val args, val input_in, val files_in)
 {
   val call = cons(name, args);
   val spec = cons(cons(call, nil), nil);
+  val input = default_bool_arg(input_in);
+  val files = default_bool_arg(files_in);
   val in_bindings = cdr(uw_get_match_context());
   val data = if3(streamp(input),
                  lazy_stream_cons(input),
diff --git a/txr.1 b/txr.1
index e1894f19..d22c16ba 100644
--- a/txr.1
+++ b/txr.1
@@ -50264,7 +50264,7 @@ and
 
 .coNP Function @ match-fun
 .synb
-.mets (match-fun < name < args < input << files )
+.mets (match-fun < name < args >> [ input <> [ files ]])
 .syne
 .desc
 The
@@ -50284,15 +50284,18 @@ pattern language, not \*(TL) and evaluated accordingly.
 The
 .meta input
 argument is a list of strings, which may be lazy. It represents the
-lines of the text stream to be processed.
+lines of the text stream to be processed. If omitted, it defaults to
+.codn nil .
 
 The
-.meta file
+.meta files
 argument is a list of filename specifications, which follow
 the same conventions as files given on the \*(TX command line. If the pattern
 function uses the
 .code @(next)
-directive, it can process these additional files.
+directive, it can process these additional files. If this argument is
+omitted, it defaults to
+.codn nil .
 
 The
 .code match-fun
-- 
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