From 3058e5f4192f8b9617ae157cb5d1e6040d79a8d9 Mon Sep 17 00:00:00 2001
From: Adam Chlipala <adamc@hcoop.net>
Date: Tue, 2 Mar 2010 09:46:17 -0500
Subject: String.isPrefix

---
 lib/ur/string.ur | 3 +++
 1 file changed, 3 insertions(+)

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

diff --git a/lib/ur/string.ur b/lib/ur/string.ur
index 07d7e6b8..f19ce174 100644
--- a/lib/ur/string.ur
+++ b/lib/ur/string.ur
@@ -53,3 +53,6 @@ fun newlines [ctx] [[Body] ~ ctx] s : xml ([Body] ++ ctx) [] [] =
     case split s #"\n" of
         None => cdata s
       | Some (s1, s2) => <xml>{[s1]}<br/>{newlines s2}</xml>
+
+fun isPrefix {Full = f, Prefix = p} =
+    length f >= length p && substring f {Start = 0, Len = length p} = p
-- 
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