From d0d3feeb4be7e15037c977a3b07f169dd4d7cf99 Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Wed, 6 Nov 2013 16:18:29 +0900
Subject: [PATCH] add when and unless macros

---
 piclib/built-in.scm | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/piclib/built-in.scm b/piclib/built-in.scm
index e4c000c4..5c93ef2b 100644
--- a/piclib/built-in.scm
+++ b/piclib/built-in.scm
@@ -115,6 +115,12 @@
 
 (define else #t)
 
+(define-macro (when test . exprs)
+  (list 'if test (cons 'begin exprs) #f))
+
+(define-macro (unless test . exprs)
+  (list 'if test #f (cons 'begin exprs)))
+
 (define-macro (and . exprs)
   (if (null? exprs)
       #t