1 {-# LANGUAGE DeriveDataTypeable #-}
3 -- | A newtype around a list of Strings which represent the MXes whose
4 -- remote forwards we don't report. This is all to avoid an orphan
5 -- instance of Configured for [String] if we had defined one in
6 -- e.g. 'OptionalConfiguration'.
9 MxList( MxList, get_mxs ) )
12 -- DC is needed only for the DCT.Configured instance of String.
13 import qualified Data.Configurator as DC()
14 import qualified Data.Configurator.Types as DCT (
18 import Data.Data (Data)
19 import System.Console.CmdArgs.Default ( Default( def ) )
22 -- | A (wrapper around a) list of MX hostnames.
25 MxList { get_mxs :: [String] }
29 -- | The default (empty) list of MXes.
31 instance Default MxList where
35 instance DCT.Configured MxList where
36 -- | This allows us to read a MxList object out of a Configurator
37 -- config file. By default Configurator wouldn't know what to do,
38 -- so we have to tell it that we expect a list, and if that list
39 -- has strings in it, we can apply the MxList constructor to
41 convert (DCT.List xs) =
42 -- mapM gives us a Maybe [String] here.
43 fmap MxList (mapM convert_string xs)
45 convert_string :: DCT.Value -> Maybe String
46 convert_string = DCT.convert
48 -- If we read anything other than a list of values out of the file,