fix bug in sample code

diff --git a/docs/users_guide/glasgow_exts.xml b/docs/users_guide/glasgow_exts.xml
index 6b41b39..9c1b2c7 100644 (file)
--- a/docs/users_guide/glasgow_exts.xml
+++ b/docs/users_guide/glasgow_exts.xml
@@ -617,7 +617,7 @@ clunky env var1 var1 = case lookup env var1 of
     Nothing -> fail
     Just val2 -> val1 + val2
 where
-  fail = val1 + val2
+  fail = var1 + var2
 </programlisting>
 
 <para>