From 719286cb036d2623ce0604bd10584f2e88c7e49e Mon Sep 17 00:00:00 2001 From: Joey Hess Date: Sun, 20 Mar 2016 13:10:48 -0400 Subject: rename module --- src/Propellor/Types/PropTypes.hs | 279 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 279 insertions(+) create mode 100644 src/Propellor/Types/PropTypes.hs (limited to 'src/Propellor/Types/PropTypes.hs') diff --git a/src/Propellor/Types/PropTypes.hs b/src/Propellor/Types/PropTypes.hs new file mode 100644 index 00000000..d3d04dca --- /dev/null +++ b/src/Propellor/Types/PropTypes.hs @@ -0,0 +1,279 @@ +{-# LANGUAGE TypeOperators, PolyKinds, DataKinds, TypeFamilies, UndecidableInstances, FlexibleInstances, GADTs #-} + +module Propellor.Types.PropTypes ( + Property(..), + mkProperty, + mkProperty', + OS(..), + PropType(..), + UnixLike, + Debian, + Buntish, + FreeBSD, + HasInfo, + (:+:), + OuterPropTypes, + ensureProperty, + tightenTargets, + pickOS, + Sing, + WithTypes, +) where + +----- DEMO ---------- + +foo :: Property (HasInfo :+: FreeBSD) +foo = mkProperty' $ \t -> do + ensureProperty t jail + +bar :: Property (Debian :+: FreeBSD) +bar = aptinstall `pickOS` jail + +aptinstall :: Property Debian +aptinstall = mkProperty $ do + return () + +jail :: Property FreeBSD +jail = mkProperty $ do + return () + +----- END DEMO ---------- + +data Property proptypes = Property proptypes (IO ()) + +mkProperty :: Sing l => IO () -> Property (WithTypes l) +mkProperty = mkProperty' . const + +mkProperty' :: Sing l => (OuterPropTypes l -> IO ()) -> Property (WithTypes l) +mkProperty' a = + let p = Property sing (a (outerPropTypes p)) + in p + +data OS + = OSDebian + | OSBuntish -- ^ A well-known Debian derivative founded by a space tourist. The actual name of this distribution is not used in Propellor per + | OSFreeBSD + deriving (Show, Eq) + +data PropType + = Targeting OS -- ^ A target OS of a Property + | WithInfo -- ^ Indicates that a Property has associated Info + deriving (Show, Eq) + +-- | Any unix-like system +type UnixLike = WithTypes '[ 'Targeting 'OSDebian, 'Targeting 'OSBuntish, 'Targeting 'OSFreeBSD ] +type Debian = WithTypes '[ 'Targeting 'OSDebian ] +type Buntish = WithTypes '[ 'Targeting 'OSBuntish ] +type FreeBSD = WithTypes '[ 'Targeting 'OSFreeBSD ] + +-- | Used to indicate that a Property adds Info to the Host where it's used. +type HasInfo = WithTypes '[ 'WithInfo ] + +-- | A family of type-level lists of [`PropType`] +data family WithTypes (x :: k) + +-- | Singletons +class Sing t where + sing :: WithTypes t + +data instance WithTypes (x :: [k]) where + Nil :: WithTypes '[] + Cons :: WithTypes x -> WithTypes xs -> WithTypes (x ': xs) + +instance (Sing x, Sing xs) => Sing (x ': xs) where sing = Cons sing sing +instance Sing '[] where sing = Nil + +-- This boilerplatw would not be needed if the singletons library were +-- used. However, we're targeting too old a version of ghc to use it yet. +data instance WithTypes (x :: PropType) where + OSDebianS :: WithTypes ('Targeting 'OSDebian) + OSBuntishS :: WithTypes ('Targeting 'OSBuntish) + OSFreeBSDS :: WithTypes ('Targeting 'OSFreeBSD) + WithInfoS :: WithTypes 'WithInfo +instance Sing ('Targeting 'OSDebian) where sing = OSDebianS +instance Sing ('Targeting 'OSBuntish) where sing = OSBuntishS +instance Sing ('Targeting 'OSFreeBSD) where sing = OSFreeBSDS +instance Sing 'WithInfo where sing = WithInfoS + +-- | Convenience type operator to combine two `WithTypes` lists. +-- +-- For example: +-- +-- > HasInfo :+: Debian +-- +-- Which is shorthand for this type: +-- +-- > WithTypes '[WithInfo, Targeting OSDebian] +type family a :+: b :: ab +type instance (WithTypes a) :+: (WithTypes b) = WithTypes (Concat a b) + +type family Concat (list1 :: [a]) (list2 :: [a]) :: [a] +type instance Concat '[] bs = bs +type instance Concat (a ': as) bs = a ': (Concat as bs) + +newtype OuterPropTypes l = OuterPropTypes (WithTypes l) + +outerPropTypes :: Property (WithTypes l) -> OuterPropTypes l +outerPropTypes (Property proptypes _) = OuterPropTypes proptypes + +-- | Use `mkProperty''` to get the `OuterPropTypes`. For example: +-- +-- > foo = Property Debian +-- > foo = mkProperty' $ \t -> do +-- > ensureProperty t (aptInstall "foo") +-- +-- The type checker will prevent using ensureProperty with a property +-- that does not support the target OSes needed by the OuterPropTypes. +-- In the example above, aptInstall must support Debian. +-- +-- The type checker will also prevent using ensureProperty with a property +-- with HasInfo in its PropTypes. Doing so would cause the info associated +-- with the property to be lost. +ensureProperty + :: + ( (Targets inner `NotSuperset` Targets outer) ~ 'CanCombineTargets + , CannotUseEnsurePropertyWithInfo inner ~ 'True + ) + => OuterPropTypes outer + -> Property (WithTypes inner) + -> IO () +ensureProperty (OuterPropTypes outerproptypes) (Property innerproptypes a) = a + +-- The name of this was chosen to make type errors a more understandable. +type family CannotUseEnsurePropertyWithInfo (l :: [a]) :: Bool +type instance CannotUseEnsurePropertyWithInfo '[] = 'True +type instance CannotUseEnsurePropertyWithInfo (t ': ts) = Not (t `EqT` 'WithInfo) && CannotUseEnsurePropertyWithInfo ts + +-- | Tightens the PropType list of a Property, to contain fewer targets. +-- +-- Anything else in the PropType list is passed through unchanged. +tightenTargets + :: + ( combined ~ Concat (NonTargets old) (Intersect (Targets old) (Targets new)) + , CannotCombineTargets old new combined ~ 'CanCombineTargets + , Sing combined + ) + => WithTypes new + -> Property (WithTypes old) + -> Property (WithTypes combined) +tightenTargets _ (Property old a) = Property sing a + +-- | Picks one of the two input properties to use, +-- depending on the targeted OS. +-- +-- If both input properties support the targeted OS, then the +-- first will be used. +pickOS + :: + ( combined ~ Union a b + , Sing combined + ) + => Property (WithTypes a) + -> Property (WithTypes b) + -> Property (WithTypes combined) +pickOS a@(Property ta ioa) b@(Property tb iob) = Property sing io + where + -- TODO pick with of ioa or iob to use based on final OS of + -- system being run on. + io = undefined + +data CheckCombineTargets = CannotCombineTargets | CanCombineTargets + +-- | Detect intersection of two lists that don't have any common targets. +-- +-- The name of this was chosen to make type errors a more understandable. +type family CannotCombineTargets (list1 :: [a]) (list2 :: [a]) (listr :: [a]) :: CheckCombineTargets +type instance CannotCombineTargets l1 l2 '[] = 'CannotCombineTargets +type instance CannotCombineTargets l1 l2 (a ': rest) = 'CanCombineTargets + +-- | Every item in the subset must be in the superset. +-- +-- The name of this was chosen to make type errors a more understandable. +type family NotSuperset (superset :: [a]) (subset :: [a]) :: CheckCombineTargets +type instance NotSuperset superset '[] = 'CanCombineTargets +type instance NotSuperset superset (s ': rest) = + If (Elem s superset) + (NotSuperset superset rest) + 'CannotCombineTargets + +type family IsTarget (a :: t) :: Bool +type instance IsTarget ('Targeting a) = 'True +type instance IsTarget 'WithInfo = 'False + +type family Targets (l :: [a]) :: [a] +type instance Targets '[] = '[] +type instance Targets (x ': xs) = + If (IsTarget x) + (x ': Targets xs) + (Targets xs) + +type family NonTargets (l :: [a]) :: [a] +type instance NonTargets '[] = '[] +type instance NonTargets (x ': xs) = + If (IsTarget x) + (Targets xs) + (x ': Targets xs) + +-- | Type level elem +type family Elem (a :: t) (list :: [t]) :: Bool +type instance Elem a '[] = 'False +type instance Elem a (b ': bs) = EqT a b || Elem a bs + +-- | Type level union. +type family Union (list1 :: [a]) (list2 :: [a]) :: [a] +type instance Union '[] list2 = list2 +type instance Union (a ': rest) list2 = + If (Elem a list2 || Elem a rest) + (Union rest list2) + (a ': Union rest list2) + +-- | Type level intersection. Duplicate list items are eliminated. +type family Intersect (list1 :: [a]) (list2 :: [a]) :: [a] +type instance Intersect '[] list2 = '[] +type instance Intersect (a ': rest) list2 = + If (Elem a list2 && Not (Elem a rest)) + (a ': Intersect rest list2) + (Intersect rest list2) + +-- | Type level equality +-- +-- This is a very clumsy implmentation, but it works back to ghc 7.6. +type family EqT (a :: t) (b :: t) :: Bool +type instance EqT ('Targeting a) ('Targeting b) = EqT a b +type instance EqT 'WithInfo 'WithInfo = 'True +type instance EqT 'WithInfo ('Targeting b) = 'False +type instance EqT ('Targeting a) 'WithInfo = 'False +type instance EqT 'OSDebian 'OSDebian = 'True +type instance EqT 'OSBuntish 'OSBuntish = 'True +type instance EqT 'OSFreeBSD 'OSFreeBSD = 'True +type instance EqT 'OSDebian 'OSBuntish = 'False +type instance EqT 'OSDebian 'OSFreeBSD = 'False +type instance EqT 'OSBuntish 'OSDebian = 'False +type instance EqT 'OSBuntish 'OSFreeBSD = 'False +type instance EqT 'OSFreeBSD 'OSDebian = 'False +type instance EqT 'OSFreeBSD 'OSBuntish = 'False +-- More modern version if the combinatiorial explosion gets too bad later: +-- +-- type family Eq (a :: PropType) (b :: PropType) where +-- Eq a a = True +-- Eq a b = False + +-- | An equivilant to the following is in Data.Type.Bool in +-- modern versions of ghc, but is included here to support ghc 7.6. +type family If (cond :: Bool) (tru :: a) (fls :: a) :: a +type instance If 'True tru fls = tru +type instance If 'False tru fls = fls +type family (a :: Bool) || (b :: Bool) :: Bool +type instance 'False || 'False = 'False +type instance 'True || 'True = 'True +type instance 'True || 'False = 'True +type instance 'False || 'True = 'True +type family (a :: Bool) && (b :: Bool) :: Bool +type instance 'False && 'False = 'False +type instance 'True && 'True = 'True +type instance 'True && 'False = 'False +type instance 'False && 'True = 'False +type family Not (a :: Bool) :: Bool +type instance Not 'False = 'True +type instance Not 'True = 'False + -- cgit v1.2.3