--- /dev/null
+-- | All exit codes that the program can return (excepting
+-- ExitSuccess).
+--
+module ExitCodes (
+ exit_no_hosts,
+ exit_no_lists,
+ exit_unparseable_host,
+ exit_unparseable_list )
+where
+
+-- | No hosts were given on the command-line or in a config file.
+--
+exit_no_hosts :: Int
+exit_no_hosts = 1
+
+
+-- | No lists were given on the command-line or in a config file.
+--
+exit_no_lists :: Int
+exit_no_lists = 2
+
+
+-- | The user gave us an RBL we couldn't parse.
+--
+exit_unparseable_list :: Int
+exit_unparseable_list = 3
+
+
+-- | The user gave us a host we couldn't parse.
+--
+exit_unparseable_host :: Int
+exit_unparseable_host = 4