Create a Usernames newtype to fix an orphan instance.

[dead/halcyon.git] / src / OptionalConfiguration.hs

diff --git a/src/OptionalConfiguration.hs b/src/OptionalConfiguration.hs
index 11add85de7ae6081755d1821cf750a0c845b4af4..77b3a06d2c42bef78908bdc09827cad73e91988d 100644 (file)
--- a/src/OptionalConfiguration.hs
+++ b/src/OptionalConfiguration.hs
@@ -16,12 +16,15 @@ module OptionalConfiguration (
 where
 
 import qualified Data.Configurator as DC
-import qualified Data.Configurator.Types as DCT
+
 import Data.Data (Data)
 import Data.Maybe (fromMaybe)
 import Data.Monoid (Monoid(..))
 import Data.Typeable (Typeable)
 
+import Usernames
+
+
 -- | The same as Cfg, except everything is optional. It's easy to
 --   merge two of these by simply dropping the Nothings in favor of
 --   the Justs. The 'usernames' are left un-maybed so that cmdargs
@@ -39,7 +42,7 @@ data OptionalCfg =
                 from_address :: Maybe String,
                 to_address :: Maybe String,
                 verbose :: Maybe Bool,
-                usernames :: [String] }
+                usernames :: Usernames }
     deriving (Show, Data, Typeable)
 
 instance Monoid OptionalCfg where
@@ -55,7 +58,7 @@ instance Monoid OptionalCfg where
              Nothing
              Nothing
              Nothing
-             []
+             (Usernames [])
 
   cfg1 `mappend` cfg2 =
     OptionalCfg
@@ -70,7 +73,7 @@ instance Monoid OptionalCfg where
       (merge (from_address cfg1) (from_address cfg2))
       (merge (to_address cfg1) (to_address cfg2))
       (merge (verbose cfg1) (verbose cfg2))
-      (usernames cfg2) -- Use only the usernames from cfg2
+      all_usernames
     where
       merge :: (Maybe a) -> (Maybe a) -> (Maybe a)
       merge Nothing Nothing   = Nothing
@@ -78,15 +81,11 @@ instance Monoid OptionalCfg where
       merge Nothing (Just x)  = Just x
       merge (Just _) (Just y) = Just y
 
-
-instance DCT.Configured [String] where
-  convert (DCT.List xs) =
-    mapM convert_string xs
-    where
-      convert_string :: DCT.Value -> Maybe String
-      convert_string = DCT.convert
-
-  convert _ = Nothing
+      -- Use only the latter usernames if there are any.
+      all_usernames =
+        usernames $ if (null (get_usernames (usernames cfg2)))
+                    then cfg1
+                    else cfg2
 
 from_rc :: IO OptionalCfg
 from_rc = do
@@ -116,4 +115,4 @@ from_rc = do
              cfg_from_address
              cfg_to_address
              cfg_verbose
-             (fromMaybe [] cfg_usernames)
+             (fromMaybe (Usernames []) cfg_usernames)