X-Git-Url: http://gitweb.michael.orlitzky.com/?p=dead%2Fhtsn.git;a=blobdiff_plain;f=src%2FOptionalConfiguration.hs;h=0913864e0bb064cfd61884e25940a1e326eda771;hp=d133432bb3c23280b00690df4c2e774edf9f19ff;hb=160caf38b6e936b6541b31b3c9bbe952ba0a4b15;hpb=bf31955186e4e3dd4e4f57cbf915fd9fc3d6b793

diff --git a/src/OptionalConfiguration.hs b/src/OptionalConfiguration.hs
index d133432..0913864 100644
--- a/src/OptionalConfiguration.hs
+++ b/src/OptionalConfiguration.hs
@@ -12,7 +12,8 @@
 
 module OptionalConfiguration (
   OptionalConfiguration(..),
-  from_rc )
+  from_rc,
+  merge_maybes )
 where
 
 import qualified Data.Configurator as DC (
@@ -31,6 +32,7 @@ import System.Directory ( getHomeDirectory )
 import System.FilePath ( (</>) )
 import System.IO.Error ( catchIOError )
 import System.Log ( Priority(..) )
+
 import Logging ( log_error )
 import TSN.FeedHosts ( FeedHosts(..) )
 
@@ -58,15 +60,22 @@ data OptionalConfiguration =
     deriving (Show, Data, Typeable)
 
 
+-- | Combine two Maybes into one, essentially mashing them
+--   together. We give precedence to the second argument when both are
+--   Justs.
+merge_maybes :: (Maybe a) -> (Maybe a) -> (Maybe a)
+merge_maybes Nothing Nothing   = Nothing
+merge_maybes (Just x) Nothing  = Just x
+merge_maybes Nothing (Just x)  = Just x
+merge_maybes (Just _) (Just y) = Just y
+
+
 -- | The Monoid instance for these lets us "combine" two
 --   OptionalConfigurations. The "combine" operation that we'd like to
 --   perform is, essentially, to mash them together. So if we have two
 --   OptionalConfigurations, each half full, we could combine them
 --   into one big one.
 --
---   One of the two must take precedence during this mashing, and we
---   choose the second one for no reason.
---
 --   This is used to merge command-line and config-file settings.
 --
 instance Monoid OptionalConfiguration where
@@ -85,19 +94,13 @@ instance Monoid OptionalConfiguration where
   cfg1 `mappend` cfg2 =
     OptionalConfiguration
       all_feed_hosts
-      (merge (log_file cfg1) (log_file cfg2))
-      (merge (log_level cfg1) (log_level cfg2))
-      (merge (password cfg1) (password cfg2))
-      (merge (output_directory cfg1) (output_directory cfg2))
-      (merge (syslog cfg1) (syslog cfg2))
-      (merge (username cfg1) (username cfg2))
+      (merge_maybes (log_file cfg1) (log_file cfg2))
+      (merge_maybes (log_level cfg1) (log_level cfg2))
+      (merge_maybes (password cfg1) (password cfg2))
+      (merge_maybes (output_directory cfg1) (output_directory cfg2))
+      (merge_maybes (syslog cfg1) (syslog cfg2))
+      (merge_maybes (username cfg1) (username cfg2))
     where
-      merge :: (Maybe a) -> (Maybe a) -> (Maybe a)
-      merge Nothing Nothing   = Nothing
-      merge (Just x) Nothing  = Just x
-      merge Nothing (Just x)  = Just x
-      merge (Just _) (Just y) = Just y
-
       -- Use only the latter feed_hosts if there are any.
       all_feed_hosts =
         feed_hosts $ if (null (get_feed_hosts (feed_hosts cfg2)))