got rid of the Attr -> Attr SetAttr hack, and use monoids for Attr

The SetAttr hack used to be needed because the hostname was part of the
Attr, and was required to be present. Now that it's moved to Host, let's
get rid of that, since it tended to waste CPU.

1 files changed, 12 insertions, 16 deletions

diff --git a/src/Propellor/Property.hs b/src/Propellor/Property.hs
index f2a4b3dd..e3d46eae 100644
--- a/src/Propellor/Property.hs
+++ b/src/Propellor/Property.hs
@@ -5,12 +5,10 @@ module Propellor.Property where
 import System.Directory
 import Control.Monad
 import Data.Monoid
-import Data.List
 import Control.Monad.IfElse
 import "mtl" Control.Monad.Reader
 
 import Propellor.Types
-import Propellor.Types.Attr
 import Propellor.Attr
 import Propellor.Engine
 import Utility.Monad
@@ -18,19 +16,19 @@ import System.FilePath
 
 -- Constructs a Property.
 property :: Desc -> Propellor Result -> Property
-property d s = Property d s id
+property d s = Property d s mempty
 
 -- | Combines a list of properties, resulting in a single property
 -- that when run will run each property in the list in turn,
 -- 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) (combineSetAttrs ps)
+propertyList desc ps = Property desc (ensureProperties ps) (combineAttrs ps)
 
 -- | Combines a list of properties, resulting in one property that
 -- ensures each in turn, stopping on failure.
 combineProperties :: Desc -> [Property] -> Property
-combineProperties desc ps = Property desc (go ps NoChange) (combineSetAttrs ps)
+combineProperties desc ps = Property desc (go ps NoChange) (combineAttrs ps)
   where
   	go [] rs = return rs
 	go (l:ls) rs = do
@@ -69,7 +67,7 @@ flagFile' p getflagfile = adjustProperty p $ \satisfy -> do
 --- | Whenever a change has to be made for a Property, causes a hook
 -- Property to also be run, but not otherwise.
 onChange :: Property -> Property -> Property
-p `onChange` hook = Property (propertyDesc p) satisfy (combineSetAttr p hook)
+p `onChange` hook = Property (propertyDesc p) satisfy (combineAttr p hook)
   where
 	satisfy = do
 		r <- ensureProperty p
@@ -130,21 +128,19 @@ revert (RevertableProperty p1 p2) = RevertableProperty p2 p1
 -- > 	! oldproperty
 -- > 	& otherproperty
 host :: HostName -> Host
-host hn = Host hn [] (\_ -> newAttr)
+host hn = Host hn [] mempty
 
 -- | Adds a property to a Host
 --
 -- Can add Properties and RevertableProperties
 (&) :: IsProp p => Host -> p -> Host
-(Host hn ps as) & p = Host hn (ps ++ [toProp p]) (setAttr p . as)
+(Host hn ps as) & p = Host hn (ps ++ [toProp p]) (as <> getAttr p)
 
 infixl 1 &
 
 -- | Adds a property to the Host in reverted form.
 (!) :: Host -> RevertableProperty -> Host
-(Host hn ps as) ! p = Host hn (ps ++ [toProp q]) (setAttr q . as)
-  where
-	q = revert p
+h ! p = h & revert p
 
 infixl 1 !
 
@@ -152,12 +148,12 @@ infixl 1 !
 adjustProperty :: Property -> (Propellor Result -> Propellor Result) -> Property
 adjustProperty p f = p { propertySatisfy = f (propertySatisfy p) }
 
--- Combines the Attr settings of two properties.
-combineSetAttr :: (IsProp p, IsProp q) => p -> q -> SetAttr
-combineSetAttr p q = setAttr p . setAttr q
+-- Combines the Attr of two properties.
+combineAttr :: (IsProp p, IsProp q) => p -> q -> Attr
+combineAttr p q = getAttr p <> getAttr q
 
-combineSetAttrs :: IsProp p => [p] -> SetAttr
-combineSetAttrs = foldl' (.) id . map setAttr
+combineAttrs :: IsProp p => [p] -> Attr
+combineAttrs = mconcat . map getAttr
 
 makeChange :: IO () -> Propellor Result
 makeChange a = liftIO a >> return MadeChange