From efa6f97eee79311cd06592ed0241acfc40561785 Mon Sep 17 00:00:00 2001
From: Adam Chlipala <adamc@hcoop.net>
Date: Tue, 15 Sep 2009 15:48:53 -0400
Subject: Filters implementation type-checking

---
 lib/ur/option.ur | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'lib/ur/option.ur')

diff --git a/lib/ur/option.ur b/lib/ur/option.ur
index 1f044002..a22cf5b5 100644
--- a/lib/ur/option.ur
+++ b/lib/ur/option.ur
@@ -7,6 +7,11 @@ fun eq [a] (_ : eq a) =
                | (Some x, Some y) => x = y
                | _ => False)
 
+fun isNone [a] x =
+    case x of
+        None => True
+      | Some _ => False
+
 fun isSome [a] x =
     case x of
         None => False
-- 
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