diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,12 @@
+reactive-banana-automation (0.2.0) upstream; urgency=medium
+
+  * Automation is now a newtype. (API change)
+  * Monoid instance for Automation to allow easily combining them.
+    (Note that in 0.1, there were inherited Monoid and Monad instances
+    for Automation, that did not work in a reasonable way.)
+
+ -- Joey Hess <id@joeyh.name>  Thu, 03 May 2018 18:54:04 -0400
+
 reactive-banana-automation (0.1.2) upstream; urgency=medium
 
   * Added ClockSignal and related functions.
diff --git a/Reactive/Banana/Automation.hs b/Reactive/Banana/Automation.hs
--- a/Reactive/Banana/Automation.hs
+++ b/Reactive/Banana/Automation.hs
@@ -17,7 +17,7 @@
 -- of using this library.
 module Reactive.Banana.Automation (
 	-- * Framework
-	Automation,
+	Automation(..),
 	MomentAutomation,
 	runAutomation,
 	observeAutomation,
@@ -76,7 +76,7 @@
 -- > data Actuators = FridgePower PowerChange deriving (Show)
 -- > 
 -- > fridge :: Automation Sensors Actuators
--- > fridge sensors actuators = do
+-- > fridge = Automation $ \sensors actuators -> do
 -- >	btemperature <- sensedBehavior (fridgeTemperature sensors)
 -- >	let bpowerchange = calcpowerchange <$> btemperature
 -- >	onBehaviorChange bpowerchange (actuators . FridgePower)
@@ -87,8 +87,17 @@
 -- >		| otherwise = Nothing
 -- >	calcpowerchange SensorUnavailable = Nothing
 -- >	allowedtemp = Range 1 4
-type Automation sensors actuators = sensors -> (actuators -> IO ()) -> MomentAutomation ()
+newtype Automation sensors actuators = Automation (sensors -> (actuators -> IO ()) -> MomentAutomation ())
 
+instance Sem.Semigroup (Automation sensors actuators) where
+	Automation a <> Automation b = Automation $ \sensors actuators -> do
+		a sensors actuators
+		b sensors actuators
+
+instance Monoid (Automation sensors actuators) where
+	mempty = Automation $ \_sensors _actuators -> return ()
+	mappend = (Sem.<>)
+
 -- | This is simply a wrapper around reactive-banana's `MomentIO`,
 -- but without the `MonadIO` instance, so an `Automation` using this monad
 -- is limited to using its sensors and actuators for IO. That allows
@@ -116,7 +125,7 @@
 	liftMoment = MomentAutomation . liftMoment
 
 setupAutomation :: Automation sensors actuators -> IO sensors -> (actuators -> IO ()) -> IO sensors
-setupAutomation automation mksensors actutators = do
+setupAutomation (Automation automation) mksensors actutators = do
 	sensors <- mksensors
 	network <- compile $ unMomentAutomation $ automation sensors actutators
 	actuate network
@@ -315,6 +324,9 @@
 --
 -- See `Reactive.Banana.Examples.nightLight` for an example
 -- of using clock signals, and how to test code that uses them.
+--
+-- It's recommended that any `Behavior` that contains a `ClockSignal`
+-- be constructed to update whenever the clock signals an update.
 data ClockSignal a = ClockSignal a
 	deriving (Show, Eq, Ord, Functor)
 
diff --git a/Reactive/Banana/Automation/Examples.hs b/Reactive/Banana/Automation/Examples.hs
--- a/Reactive/Banana/Automation/Examples.hs
+++ b/Reactive/Banana/Automation/Examples.hs
@@ -1,5 +1,3 @@
-{-# OPTIONS_GHC -fno-warn-unused-imports #-}
-
 -- | `Automation` examples. View source for the code.
 --
 -- These examples are tested by doctest when building this library.
@@ -12,7 +10,7 @@
 import Reactive.Banana.Automation
 import Data.Time.Clock.POSIX
 import Data.Time.LocalTime
-import Data.Time.Calendar -- imported for doctest examples
+import Data.Time.Calendar
 
 -- | We'll use a single Sensors type containing all the sensors
 -- used by the examples below.
@@ -61,7 +59,7 @@
 -- >>> runner $ \sensors -> fridgeTemperature sensors =: 0.5
 -- [FridgePower PowerOff]
 fridge :: Automation Sensors Actuators
-fridge sensors actuators = do
+fridge = Automation $ \sensors actuators -> do
 	-- Create a Behavior that reflects the most recently reported
 	-- temperature of the fridge.
 	btemperature <- sensedBehavior (fridgeTemperature sensors)
@@ -97,7 +95,7 @@
 -- >>> runner $ \sensors -> sensedAt 400 (motionSensor sensors) False
 -- [LightSwitch PowerOff]
 motionActivatedLight :: Automation Sensors Actuators
-motionActivatedLight sensors actuators = do
+motionActivatedLight = Automation $ \sensors actuators -> do
 	-- Make an Event that contains the time elapsed since the last
 	-- detected motion.
 	timesincemotion <- elapsedTimeSince (== True)
@@ -128,7 +126,7 @@
 -- >>> runner $ \sensors -> clockSignalAt (LocalTime day midday) (clock sensors)
 -- [LightSwitch PowerOff]
 nightLight :: Automation Sensors Actuators
-nightLight sensors actuators = do
+nightLight = Automation $ \sensors actuators -> do
 	bclock <- clockSignalBehavior (clock sensors)
 	let bhour = (fmap . fmap) (todHour . localTimeOfDay) <$> bclock
 	let lightchange = calcchange <$> bhour
@@ -144,10 +142,10 @@
 --
 -- While it could be used to drive a real LCD, this is mostly useful
 -- for testing behaviors.
-showBehaviorLCDDisplay :: Show a => (Sensors -> MomentAutomation (Behavior a)) -> Automation Sensors Actuators
-showBehaviorLCDDisplay mkb sensors actuators = do
+showBehaviorLCDDisplay :: (a -> String) -> (Sensors -> MomentAutomation (Behavior a)) -> Automation Sensors Actuators
+showBehaviorLCDDisplay fmt mkb = Automation $ \sensors actuators -> do
 	b <- mkb sensors
-	onBehaviorChange b (actuators . LCDDisplay . show)
+	onBehaviorChange b (actuators . LCDDisplay . fmt)
 
 -- | The rain gauge sensor is a tipping bucket type; the bucket collects 0.01
 -- inches of rain and then tips, which triggers the `rainGaugeTipSensor`.
@@ -155,7 +153,7 @@
 --
 -- To test this behavior, we can use `showBehaviorLCDDisplay`:
 --
--- >>> runner <- observeAutomation (showBehaviorLCDDisplay totalRainfall) mkSensors
+-- >>> runner <- observeAutomation (showBehaviorLCDDisplay show totalRainfall) mkSensors
 -- >>> runner $ \sensors -> sensed (rainGaugeTipSensor sensors) ()
 -- [LCDDisplay "1"]
 -- >>> runner $ \sensors -> sensed (rainGaugeTipSensor sensors) ()
@@ -167,13 +165,14 @@
 	tipevents <- sensedEvent (rainGaugeTipSensor sensors)
 	accumB 0 $ const succ <$> tipevents
 
--- | This behavior contains the total rainfall since a given `TimeOfDay`.
+-- | This behavior contains the total rainfall since a specified `TimeOfDay`,
+-- and is timestamped with the last clock signal.
 --
 -- To test this behavior, we can use `showBehaviorLCDDisplay`,
 -- providing both clock signals and `rainGaugeTipSensor` events:
 --
 -- >>> let day = fromGregorian 2018 1 1
--- >>> runner <- observeAutomation (showBehaviorLCDDisplay $ totalRainfallSince midnight) mkSensors
+-- >>> runner <- observeAutomation (showBehaviorLCDDisplay (show . value) $ totalRainfallSince midnight) mkSensors
 -- >>> runner $ \sensors -> clockSignalAt (LocalTime day (TimeOfDay 13 0 0)) (clock sensors)
 -- [LCDDisplay "0"]
 -- >>> runner $ \sensors -> sensed (rainGaugeTipSensor sensors) ()
@@ -190,7 +189,7 @@
 -- [LCDDisplay "1"]
 -- >>> runner $ \sensors -> sensed (rainGaugeTipSensor sensors) ()
 -- [LCDDisplay "2"]
-totalRainfallSince :: TimeOfDay -> Sensors -> MomentAutomation (Behavior Integer)
+totalRainfallSince :: TimeOfDay -> Sensors -> MomentAutomation (Behavior (Timestamped (ClockSignal LocalTime) Integer))
 totalRainfallSince tod sensors = do
 	clockevents <- getEventFrom (clock sensors)
 	bclock <- clockSignalBehavior (clock sensors)
@@ -198,20 +197,22 @@
 	-- The tip events, with the tip signal replaced with
 	-- the clock time when it occurred.
 	let tiptimes = bclock <@ tipevents
-	-- Combine clock ticks and tip events, with the function
+	-- Combine clock ticks and tip events, with a function
 	-- to apply to the running total for each.
 	let combined = unionWith (\(f1, t1) (f2, t2) -> (f1 . f2, max t1 t2))
 		((\e -> (id, e)) <$> fmap Just clockevents)
 		((\e -> (succ, e)) <$> tiptimes)
-	fmap fst <$> (accumB (0, Nothing) $ go <$> combined)
+	let epoch = LocalTime (fromGregorian 1 1 1) midnight
+	let initial = (Timestamped (ClockSignal epoch) 0, Nothing)
+	fmap fst <$> (accumB initial $ go <$> combined)
   where
-	go (f, Just (ClockSignal t)) (n, Just lastzero) =
+	go (f, Just (ClockSignal t)) (Timestamped _ n, Just lastzero) =
 		let nextzero = succ lastzero
 		in if t > LocalTime nextzero tod
-			then (0, Just nextzero)
-			else (f n, Just lastzero)
-	go (f, Just (ClockSignal t)) (n, Nothing) =
-		(f n, Just (localDay t))
+			then (Timestamped (ClockSignal t) 0, Just nextzero)
+			else (Timestamped (ClockSignal t) (f n), Just lastzero)
+	go (f, Just (ClockSignal t)) ((Timestamped _ n), Nothing) =
+		(Timestamped (ClockSignal t) (f n), Just (localDay t))
 	go (_, Nothing) v = v
 
 -- | Turns on the sprinklers for an hour each day starting from
@@ -225,13 +226,13 @@
 -- >>> runner $ \sensors -> sensed (rainGaugeTipSensor sensors) ()
 -- [SprinklerSwitch PowerOff]
 -- >>> runner $ \sensors -> clockSignalAt (LocalTime day (TimeOfDay 0 1 0)) (clock sensors)
--- [SprinklerSwitch PowerOff,SprinklerSwitch PowerOn]
+-- [SprinklerSwitch PowerOn]
 -- >>> runner $ \sensors -> clockSignalAt (LocalTime day (TimeOfDay 0 2 0)) (clock sensors)
--- [SprinklerSwitch PowerOn,SprinklerSwitch PowerOn]
+-- [SprinklerSwitch PowerOn]
 -- >>> runner $ \sensors -> clockSignalAt (LocalTime day (TimeOfDay 1 2 0)) (clock sensors)
--- [SprinklerSwitch PowerOn,SprinklerSwitch PowerOff]
+-- [SprinklerSwitch PowerOff]
 -- >>> runner $ \sensors -> clockSignalAt (LocalTime day (TimeOfDay 1 3 0)) (clock sensors)
--- [SprinklerSwitch PowerOff,SprinklerSwitch PowerOff]
+-- [SprinklerSwitch PowerOff]
 -- >>> runner $ \sensors -> sensed (rainGaugeTipSensor sensors) ()
 -- [SprinklerSwitch PowerOff]
 -- >>> runner $ \sensors -> sensed (rainGaugeTipSensor sensors) ()
@@ -239,17 +240,37 @@
 -- >>> runner $ \sensors -> sensed (rainGaugeTipSensor sensors) ()
 -- [SprinklerSwitch PowerOff]
 -- >>> runner $ \sensors -> clockSignalAt (LocalTime day (TimeOfDay 0 1 0)) (clock sensors)
--- [SprinklerSwitch PowerOff,SprinklerSwitch PowerOff]
+-- [SprinklerSwitch PowerOff]
 sprinklersStartingAt :: TimeOfDay -> Automation Sensors Actuators
-sprinklersStartingAt starttod sensors actuators = do
+sprinklersStartingAt starttod = Automation $ \sensors actuators -> do
+	-- This contains a ClockSignal, so we know it should update
+	-- whenever the clock does, and so we don't need to add in a
+	-- separate behavior for the clock.
 	brainfall <- totalRainfallSince starttod sensors
-	bclock <- clockSignalBehavior (clock sensors)
-	let b = calcchange <$> bclock <*> brainfall
+	let b = calcchange <$> brainfall
 	onBehaviorChangeMaybe b (actuators . SprinklerSwitch)
   where
 	stoptod = starttod { todHour = (todHour starttod + 1) `mod` 24 }
-	calcchange (Just (ClockSignal t)) rain
+	calcchange (Timestamped (ClockSignal t) rain)
 		| rain >= 3 = Just PowerOff
 		| localTimeOfDay t >= starttod && localTimeOfDay t < stoptod = Just PowerOn
 		| otherwise = Just PowerOff
-	calcchange Nothing _ = Nothing
+
+-- | `Automation` is a `Monoid`, so it's easy to combine several
+-- smaller automations like those above into a larger one.
+--
+-- >>> let day = fromGregorian 2018 1 1
+-- >>> runner <- observeAutomation thisHouse mkSensors 
+-- >>> runner $ \sensors -> clockSignalAt (LocalTime day midnight) (clock sensors)
+-- [LightSwitch PowerOn,SprinklerSwitch PowerOn]
+-- >>> runner $ \sensors -> fridgeTemperature sensors =: 6
+-- [FridgePower PowerOn]
+-- >>> runner $ \sensors -> sensedAt 0 (motionSensor sensors) True
+-- [LightSwitch PowerOn]
+thisHouse :: Automation Sensors Actuators
+thisHouse = mconcat
+	[ fridge
+	, nightLight
+	, motionActivatedLight
+	, sprinklersStartingAt midnight
+	]
diff --git a/reactive-banana-automation.cabal b/reactive-banana-automation.cabal
--- a/reactive-banana-automation.cabal
+++ b/reactive-banana-automation.cabal
@@ -1,5 +1,5 @@
 Name: reactive-banana-automation
-Version: 0.1.2
+Version: 0.2.0
 Cabal-Version: >= 1.8
 License: AGPL-3
 Maintainer: Joey Hess <id@joeyh.name>