From 8a85e624724ef2a01f930c05674b044aa250b565 Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Sat, 9 Nov 2013 14:27:50 +0900
Subject: [PATCH] add a note about undef values

---
 include/picrin/value.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/picrin/value.h b/include/picrin/value.h
index 6807177a..e7c9bb81 100644
--- a/include/picrin/value.h
+++ b/include/picrin/value.h
@@ -3,6 +3,11 @@
 
 typedef int pic_sym;
 
+/**
+ * `undef` values never seen from user-end: that is,
+ *  it's used only for repsenting internal special state
+ */
+
 enum pic_vtype {
   PIC_VTYPE_NIL = 1,
   PIC_VTYPE_TRUE,