Clean up the configurator code in the CLI app.

[dead/harbl.git] / harbl-cli / src / Hosts.hs

diff --git a/harbl-cli/src/Hosts.hs b/harbl-cli/src/Hosts.hs
index 020484dff1dc1872fe6e742d61fd6c2121fcacfb..83bf7c3492b22d5a2a333dc001ebfc9a36a67ad2 100644 (file)
--- a/harbl-cli/src/Hosts.hs
+++ b/harbl-cli/src/Hosts.hs
@@ -3,45 +3,33 @@
 --   [String] if we had defined one in e.g. 'OptionalConfiguration'.
 --
 {-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
 
 module Hosts ( Hosts(..) )
 where
 
--- DC is needed only for the DCT.Configured instance of String.
-import qualified Data.Configurator as DC()
-import qualified Data.Configurator.Types as DCT (
-  Configured,
-  Value( List ),
-  convert )
+import Data.Configurator () -- Needed for predefined instances.
+import Data.Configurator.Types ( Configured(..) )
+import Data.Monoid ( Monoid )
 import Data.Data ( Data )
 import System.Console.CmdArgs.Default ( Default(..) )
 import Data.Typeable ( Typeable )
 
+import Configurator ( convert_newtype_list )
+
 
 -- | A (wrapper around a) list of hosts.
 --
 newtype Hosts =
   Hosts { get_hosts :: [String] }
-    deriving (Data, Show, Typeable)
+    deriving (Data, Monoid, Show, Typeable)
 
 
 -- | The default list of hosts. It's empty.
 --
 instance Default Hosts where def = Hosts []
 
-instance DCT.Configured Hosts where
+instance Configured Hosts where
   -- | This allows us to read a Hosts object out of a Configurator
-  --   config file. By default Configurator wouldn't know what to do,
-  --   so we have to tell it that we expect a list, and if that list
-  --   has strings in it, we can apply the Hosts constructor to
-  --   it.
-  convert (DCT.List xs) =
-    -- mapM gives us a Maybe [String] here.
-    fmap Hosts (mapM convert_string xs)
-    where
-      convert_string :: DCT.Value -> Maybe String
-      convert_string = DCT.convert
-
-  -- If we read anything other than a list of values out of the file,
-  -- fail.
-  convert _ = Nothing
+  --   config file: by default Configurator wouldn't know what to do.
+  convert = convert_newtype_list Hosts