-- | Serializable closures for distributed programming. This package builds -- a "remotable closure" abstraction on top of -- <https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#static-pointers static pointers>. -- See -- <https://ocharles.org.uk/blog/guest-posts/2014-12-23-static-pointers.html this blog post> -- for a longer introduction. {-# LANGUAGE ConstraintKinds #-} {-# LANGUAGE CPP #-} {-# LANGUAGE ExplicitNamespaces #-} {-# LANGUAGE FunctionalDependencies #-} {-# LANGUAGE GeneralizedNewtypeDeriving #-} {-# LANGUAGE MultiParamTypeClasses #-} {-# LANGUAGE StaticPointers #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE UndecidableInstances #-} #if __GLASGOW_HASKELL__ >= 800 {-# LANGUAGE UndecidableSuperClasses #-} #endif module Control.Distributed.Closure ( Serializable -- * Closures , Closure , closure , unclosure , cpure , cap , cmap , cduplicate -- * Special closures , WrappedArrowClosure(..) , type (/->) -- * Closure dictionaries -- $static-dicts , Dict(..) , Static(..) ) where import Control.Distributed.Closure.Internal import Data.Binary (Binary) import Data.Constraint (Dict(..)) import Data.Typeable (Typeable) -- $static-dicts -- -- A 'Dict' reifies a constraint in the form of a first class value. The 'Dict' -- type is not serializable: how do you serialize the constraint that values of -- this type carry? Whereas, for any constraint @c@, a value of type @'Closure' -- ('Dict' c)@ /can/ be serialized and sent over the wire, just like any -- 'Closure'. A /static dictionary/ for some constraint @c@ is a value of type -- @'Closure' ('Dict' c)@. -- | It's often useful to create a static dictionary on-the-fly given any -- constraint. Morally, all type class constraints have associated static -- dictionaries, since these are either global values or simple combinations -- thereof. But GHC doesn't yet know how to invent a static dictionary on-demand -- yet given any type class constraint, so we'll have to do it manually for the -- time being. By defining instances of this type class manually, or via -- 'Control.Distributed.Closure.TH.withStatic' if it becomes too tedious. class c => Static c where closureDict :: Closure (Dict c) instance (Static c1, Static c2, Typeable c1, Typeable c2, (c1, c2)) => Static (c1, c2) where closureDict :: Closure (Dict (c1, c2)) closureDict = static forall (c1 :: Constraint) (c2 :: Constraint). Dict c1 -> Dict c2 -> Dict (c1, c2) f forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict where f :: Dict c1 -> Dict c2 -> Dict (c1, c2) f :: forall (c1 :: Constraint) (c2 :: Constraint). Dict c1 -> Dict c2 -> Dict (c1, c2) f Dict c1 Dict Dict c2 Dict = forall (a :: Constraint). a => Dict a Dict instance (Static c1, Static c2, Static c3, Typeable c1, Typeable c2, Typeable c3, (c1, c2, c3)) => Static (c1, c2, c3) where closureDict :: Closure (Dict (c1, c2, c3)) closureDict = static forall (c1 :: Constraint) (c2 :: Constraint) (c3 :: Constraint). Dict c1 -> Dict c2 -> Dict c3 -> Dict (c1, c2, c3) f forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict where f :: Dict c1 -> Dict c2 -> Dict c3 -> Dict (c1, c2, c3) f :: forall (c1 :: Constraint) (c2 :: Constraint) (c3 :: Constraint). Dict c1 -> Dict c2 -> Dict c3 -> Dict (c1, c2, c3) f Dict c1 Dict Dict c2 Dict Dict c3 Dict = forall (a :: Constraint). a => Dict a Dict instance (Static c1, Static c2, Static c3, Static c4, Typeable c1, Typeable c2, Typeable c3, Typeable c4, (c1, c2, c3, c4)) => Static (c1, c2, c3, c4) where closureDict :: Closure (Dict (c1, c2, c3, c4)) closureDict = static forall (c1 :: Constraint) (c2 :: Constraint) (c3 :: Constraint) (c4 :: Constraint). Dict c1 -> Dict c2 -> Dict c3 -> Dict c4 -> Dict (c1, c2, c3, c4) f forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict where f :: Dict c1 -> Dict c2 -> Dict c3 -> Dict c4 -> Dict (c1, c2, c3, c4) f :: forall (c1 :: Constraint) (c2 :: Constraint) (c3 :: Constraint) (c4 :: Constraint). Dict c1 -> Dict c2 -> Dict c3 -> Dict c4 -> Dict (c1, c2, c3, c4) f Dict c1 Dict Dict c2 Dict Dict c3 Dict Dict c4 Dict = forall (a :: Constraint). a => Dict a Dict instance (Static c1, Static c2, Static c3, Static c4, Static c5, Typeable c1, Typeable c2, Typeable c3, Typeable c4, Typeable c5, (c1, c2, c3, c4, c5)) => Static (c1, c2, c3, c4, c5) where closureDict :: Closure (Dict (c1, c2, c3, c4, c5)) closureDict = static forall (c1 :: Constraint) (c2 :: Constraint) (c3 :: Constraint) (c4 :: Constraint) (c5 :: Constraint). Dict c1 -> Dict c2 -> Dict c3 -> Dict c4 -> Dict c5 -> Dict (c1, c2, c3, c4, c5) f forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict where f :: Dict c1 -> Dict c2 -> Dict c3 -> Dict c4 -> Dict c5 -> Dict (c1, c2, c3, c4, c5) f :: forall (c1 :: Constraint) (c2 :: Constraint) (c3 :: Constraint) (c4 :: Constraint) (c5 :: Constraint). Dict c1 -> Dict c2 -> Dict c3 -> Dict c4 -> Dict c5 -> Dict (c1, c2, c3, c4, c5) f Dict c1 Dict Dict c2 Dict Dict c3 Dict Dict c4 Dict Dict c5 Dict = forall (a :: Constraint). a => Dict a Dict instance (Static c1, Static c2, Static c3, Static c4, Static c5, Static c6, Typeable c1, Typeable c2, Typeable c3, Typeable c4, Typeable c5, Typeable c6, (c1, c2, c3, c4, c5, c6)) => Static (c1, c2, c3, c4, c5, c6) where closureDict :: Closure (Dict (c1, c2, c3, c4, c5, c6)) closureDict = static forall (c1 :: Constraint) (c2 :: Constraint) (c3 :: Constraint) (c4 :: Constraint) (c5 :: Constraint) (c6 :: Constraint). Dict c1 -> Dict c2 -> Dict c3 -> Dict c4 -> Dict c5 -> Dict c6 -> Dict (c1, c2, c3, c4, c5, c6) f forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict forall a b. Typeable a => Closure (a -> b) -> Closure a -> Closure b `cap` forall (c :: Constraint). Static c => Closure (Dict c) closureDict where f :: Dict c1 -> Dict c2 -> Dict c3 -> Dict c4 -> Dict c5 -> Dict c6 -> Dict (c1, c2, c3, c4, c5, c6) f :: forall (c1 :: Constraint) (c2 :: Constraint) (c3 :: Constraint) (c4 :: Constraint) (c5 :: Constraint) (c6 :: Constraint). Dict c1 -> Dict c2 -> Dict c3 -> Dict c4 -> Dict c5 -> Dict c6 -> Dict (c1, c2, c3, c4, c5, c6) f Dict c1 Dict Dict c2 Dict Dict c3 Dict Dict c4 Dict Dict c5 Dict Dict c6 Dict = forall (a :: Constraint). a => Dict a Dict -- instance (Static c1, Static c2, Typeable c1, Typeable c2, (c1, c2)) => Static (c1, c2) where -- closureDict = static pairDict `cap` closureDict `cap` closureDict -- | A newtype-wrapper useful for defining instances of classes indexed by -- higher-kinded types. newtype WrappedArrowClosure a b = WrapArrowClosure { forall a b. WrappedArrowClosure a b -> Closure (a -> b) unwrapClosureArrow :: Closure (a -> b) } deriving (Get (WrappedArrowClosure a b) [WrappedArrowClosure a b] -> Put WrappedArrowClosure a b -> Put forall t. (t -> Put) -> Get t -> ([t] -> Put) -> Binary t forall a b. (Typeable a, Typeable b) => Get (WrappedArrowClosure a b) forall a b. (Typeable a, Typeable b) => [WrappedArrowClosure a b] -> Put forall a b. (Typeable a, Typeable b) => WrappedArrowClosure a b -> Put putList :: [WrappedArrowClosure a b] -> Put $cputList :: forall a b. (Typeable a, Typeable b) => [WrappedArrowClosure a b] -> Put get :: Get (WrappedArrowClosure a b) $cget :: forall a b. (Typeable a, Typeable b) => Get (WrappedArrowClosure a b) put :: WrappedArrowClosure a b -> Put $cput :: forall a b. (Typeable a, Typeable b) => WrappedArrowClosure a b -> Put Binary) infixr 0 /-> type (/->) = WrappedArrowClosure