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diff lib/ur/option.ur @ 944:da3ec6014d2f

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Filters implementation type-checking
author Adam Chlipala <adamc@hcoop.net>
date Tue, 15 Sep 2009 15:48:53 -0400
parents 0d30e6338c65
children 8c37699de273
line wrap: on
line diff
--- a/lib/ur/option.ur	Tue Sep 15 13:07:57 2009 -0400
+++ b/lib/ur/option.ur	Tue Sep 15 15:48:53 2009 -0400
@@ -7,6 +7,11 @@
                | (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