1 files changed, 44 insertions, 19 deletions

diff --git a/Propellor/Property.hs b/Propellor/Property.hs
index e7ec704d..3a3c1cb1 100644
--- a/Propellor/Property.hs
+++ b/Propellor/Property.hs
@@ -1,17 +1,22 @@
+{-# LANGUAGE PackageImports #-}
+
 module Propellor.Property where
 
 import System.Directory
 import Control.Monad
 import Data.Monoid
+import Control.Monad.IfElse
+import "mtl" Control.Monad.Reader
 
 import Propellor.Types
+import Propellor.Types.Attr
 import Propellor.Engine
 import Utility.Monad
 
-makeChange :: IO () -> IO Result
-makeChange a = a >> return MadeChange
+makeChange :: IO () -> Propellor Result
+makeChange a = liftIO a >> return MadeChange
 
-noChange :: IO Result
+noChange :: Propellor Result
 noChange = return NoChange
 
 -- | Combines a list of properties, resulting in a single property
@@ -19,7 +24,7 @@ noChange = return NoChange
 -- and print out the description of each as it's run. Does not stop
 -- on failure; does propigate overall success/failure.
 propertyList :: Desc -> [Property] -> Property
-propertyList desc ps = Property desc $ ensureProperties' ps
+propertyList desc ps = Property desc $ ensureProperties ps
 
 -- | Combines a list of properties, resulting in one property that
 -- ensures each in turn, stopping on failure.
@@ -33,18 +38,29 @@ combineProperties desc ps = Property desc $ go ps NoChange
 			FailedChange -> return FailedChange
 			_ -> go ls (r <> rs)
 
+-- | Combines together two properties, resulting in one property
+-- that ensures the first, and if the first succeeds, ensures the second.
+-- The property uses the description of the first property.
+before :: Property -> Property -> Property
+p1 `before` p2 = Property (propertyDesc p1) $ do
+	r <- ensureProperty p1
+	case r of
+		FailedChange -> return FailedChange
+		_ -> ensureProperty p2
+
 -- | Makes a perhaps non-idempotent Property be idempotent by using a flag
 -- file to indicate whether it has run before.
 -- Use with caution.
 flagFile :: Property -> FilePath -> Property
 flagFile property flagfile = Property (propertyDesc property) $
-	go =<< doesFileExist flagfile
+	go =<< liftIO (doesFileExist flagfile)
   where
 	go True = return NoChange
 	go False = do
 		r <- ensureProperty property
-		when (r == MadeChange) $
-			writeFile flagfile ""
+		when (r == MadeChange) $ liftIO $ 
+			unlessM (doesFileExist flagfile) $
+				writeFile flagfile ""
 		return r
 
 --- | Whenever a change has to be made for a Property, causes a hook
@@ -64,13 +80,13 @@ infixl 1 ==>
 
 -- | Makes a Property only be performed when a test succeeds.
 check :: IO Bool -> Property -> Property
-check c property = Property (propertyDesc property) $ ifM c
+check c property = Property (propertyDesc property) $ ifM (liftIO c)
 	( ensureProperty property
 	, return NoChange
 	)
 
 boolProperty :: Desc -> IO Bool -> Property
-boolProperty desc a = Property desc $ ifM a
+boolProperty desc a = Property desc $ ifM (liftIO a)
 	( return MadeChange
 	, return FailedChange
 	)
@@ -79,17 +95,26 @@ boolProperty desc a = Property desc $ ifM a
 revert :: RevertableProperty -> RevertableProperty
 revert (RevertableProperty p1 p2) = RevertableProperty p2 p1
 
--- | Starts a list of Properties
-props :: [Property]
-props = []
+-- | Starts accumulating the properties of a Host.
+--
+-- > host "example.com"
+-- > 	& someproperty
+-- > 	! oldproperty
+-- > 	& otherproperty
+host :: HostName -> Host
+host hn = Host [] (\_ -> newAttr hn)
+
+-- | Adds a property to a Host
+-- Can add Properties, RevertableProperties, and AttrProperties
+(&) :: IsProp p => Host -> p -> Host
+(Host ps as) & p = Host (ps ++ [toProp p]) (getAttr p . as)
 
--- | Adds a property to the list.
--- Can add both Properties and RevertableProperties.
-(&) :: IsProp p => [Property] -> p -> [Property]
-ps & p = ps ++ [toProp p]
 infixl 1 &
 
--- | Adds a property to the list in reverted form.
-(!) :: [Property] -> RevertableProperty -> [Property]
-ps ! p = ps ++ [toProp $ revert p]
+-- | Adds a property to the Host in reverted form.
+(!) :: Host -> RevertableProperty -> Host
+(Host ps as) ! p = Host (ps ++ [toProp q]) (getAttr q . as)
+  where
+	q = revert p
+
 infixl 1 !