don't need Maybe ElapsedTime

Make it a monoid and use mempty = 0

1 files changed, 6 insertions, 2 deletions

diff --git a/Types.hs b/Types.hs
index 75d22cf..678455c 100644
--- a/Types.hs
+++ b/Types.hs
@@ -60,7 +60,7 @@ instance DataSize a => DataSize (Message a) where
 data Activity a = Activity
 	{ activity :: a
 	, prevActivity :: Maybe Hash
-	, elapsedTime :: Maybe ElapsedTime
+	, elapsedTime :: ElapsedTime
 	, activitySignature :: Signature
 	}
 	deriving (Show, Generic)
@@ -68,7 +68,7 @@ data Activity a = Activity
 instance DataSize a => DataSize (Activity a) where
 	dataSize a = dataSize (activity a) 
 		+ maybe 0 dataSize (prevActivity a)
-		+ maybe 0 dataSize (elapsedTime a)
+		+ dataSize (elapsedTime a)
 		+ dataSize (activitySignature a)
 
 -- | A control message, which can be sent asynchronously.
@@ -157,6 +157,10 @@ newtype ElapsedTime = ElapsedTime Double
 mkElapsedTime :: POSIXTime -> POSIXTime -> ElapsedTime
 mkElapsedTime start end = ElapsedTime $ fromRational $ toRational (end - start)
 
+instance Monoid ElapsedTime where
+	mempty = ElapsedTime 0
+	mappend (ElapsedTime a) (ElapsedTime b) = ElapsedTime (a+b)
+
 instance DataSize ElapsedTime where
 	dataSize _ = 16 -- 128 bit Double