From c26fc144f31958b1a1870cc772e8336af18c97e5 Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Sat, 28 Jun 2014 12:07:56 +0900
Subject: [PATCH] added null operator to (picrin control list)

---
 contrib/20.for/piclib/for.scm | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/contrib/20.for/piclib/for.scm b/contrib/20.for/piclib/for.scm
index bd421ef8..d37afd9f 100644
--- a/contrib/20.for/piclib/for.scm
+++ b/contrib/20.for/piclib/for.scm
@@ -15,4 +15,7 @@
   (define (yield x)
     (list x))
 
-  (export for in yield))
+  (define (null . x)
+    '())
+
+  (export for in yield null))