{-# LANGUAGE CPP #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeOperators #-} #ifndef MIN_VERSION_base #define MIN_VERSION_base(x,y,z) 0 #endif module Data.Copointed where import Control.Applicative import Data.Default.Class import GHC.Generics #ifdef MIN_VERSION_comonad import Control.Comonad.Trans.Env import Control.Comonad.Trans.Store import Control.Comonad.Trans.Traced #if !(MIN_VERSION_comonad(4,3,0)) import Data.Functor.Coproduct #endif #endif #ifdef MIN_VERSION_containers import Data.Tree #endif #ifdef MIN_VERSION_semigroupoids import Data.Functor.Bind #endif #if defined(MIN_VERSION_semigroups) || (MIN_VERSION_base(4,9,0)) import Data.Semigroup as Semigroup import Data.List.NonEmpty (NonEmpty(..)) #endif import qualified Data.Monoid as Monoid #ifdef MIN_VERSION_tagged import Data.Tagged #endif #if defined(MIN_VERSION_transformers) || (MIN_VERSION_base(4,8,0)) import Data.Functor.Identity #endif #if defined(MIN_VERSION_transformers) || (MIN_VERSION_base(4,9,0)) import Data.Functor.Sum as F import Data.Functor.Compose #endif #ifdef MIN_VERSION_transformers import Data.Functor.Reverse import Control.Applicative.Backwards import Control.Applicative.Lift as Applicative import Control.Monad.Trans.Identity import qualified Control.Monad.Trans.Writer.Lazy as Lazy import qualified Control.Monad.Trans.Writer.Strict as Strict #endif -- | 'Copointed' does not require a 'Functor', as the only relationship -- between 'copoint' and 'fmap' is given by a free theorem. class Copointed p where copoint :: p a -> a instance Copointed ((,) a) where copoint = snd instance Copointed ((,,) a b) where copoint (_,_,a) = a instance Copointed ((,,,) a b c) where copoint (_,_,_,a) = a instance Default m => Copointed ((->)m) where copoint f = f def instance Copointed m => Copointed (WrappedMonad m) where copoint = copoint . unwrapMonad #ifdef MIN_VERSION_comonad instance (Default m, Copointed w) => Copointed (TracedT m w) where copoint (TracedT w) = copoint w def instance Copointed w => Copointed (EnvT e w) where copoint = copoint . lowerEnvT instance Copointed w => Copointed (StoreT s w) where copoint (StoreT wf s) = copoint wf s #endif #ifdef MIN_VERSION_comonad #if !(MIN_VERSION_comonad(4,3,0)) instance (Copointed p, Copointed q) => Copointed (Coproduct p q) where copoint = coproduct copoint copoint #endif #endif #ifdef MIN_VERSION_containers instance Copointed Tree where copoint = rootLabel #endif #ifdef MIN_VERSION_tagged instance Copointed (Tagged a) where copoint = unTagged #endif #if defined(MIN_VERSION_transformers) || (MIN_VERSION_base(4,8,0)) instance Copointed Identity where copoint = runIdentity #endif #if defined(MIN_VERSION_transformers) || (MIN_VERSION_base(4,9,0)) instance (Copointed p, Copointed q) => Copointed (Compose p q) where copoint = copoint . copoint . getCompose instance (Copointed f, Copointed g) => Copointed (F.Sum f g) where copoint (F.InL m) = copoint m copoint (F.InR m) = copoint m #endif #ifdef MIN_VERSION_transformers instance Copointed f => Copointed (Backwards f) where copoint = copoint . forwards instance Copointed f => Copointed (Applicative.Lift f) where copoint (Pure a) = a copoint (Other fa) = copoint fa instance Copointed f => Copointed (Reverse f) where copoint = copoint . getReverse instance Copointed m => Copointed (IdentityT m) where copoint = copoint . runIdentityT instance Copointed m => Copointed (Lazy.WriterT w m) where copoint = fst . copoint . Lazy.runWriterT instance Copointed m => Copointed (Strict.WriterT w m) where copoint = fst . copoint . Strict.runWriterT #endif instance Copointed Monoid.Dual where copoint = Monoid.getDual instance Copointed Monoid.Sum where copoint = Monoid.getSum instance Copointed Monoid.Product where copoint = Monoid.getProduct #if defined(MIN_VERSION_semigroups) || (MIN_VERSION_base(4,9,0)) instance Copointed NonEmpty where copoint ~(a :| _) = a instance Copointed Semigroup.First where copoint = Semigroup.getFirst instance Copointed Semigroup.Last where copoint = Semigroup.getLast instance Copointed Semigroup.Max where copoint = Semigroup.getMax instance Copointed Semigroup.Min where copoint = Semigroup.getMin instance Copointed WrappedMonoid where copoint = unwrapMonoid #endif #ifdef MIN_VERSION_semigroups #if MIN_VERSION_semigroups(0,16,2) #define HAVE_ARG 1 #endif #elif MIN_VERSION_base(4,9,0) #define HAVE_ARG 1 #endif #ifdef HAVE_ARG instance Copointed (Arg a) where copoint (Arg _ b) = b #endif #ifdef MIN_VERSION_semigroupoids instance Copointed f => Copointed (WrappedApplicative f) where copoint = copoint . unwrapApplicative instance Copointed f => Copointed (MaybeApply f) where copoint (MaybeApply (Left fa)) = copoint fa copoint (MaybeApply (Right a)) = a #endif instance Copointed Par1 where copoint = unPar1 instance Copointed f => Copointed (M1 i c f) where copoint = copoint . unM1 instance Copointed f => Copointed (Rec1 f) where copoint = copoint . unRec1 instance (Copointed f, Copointed g) => Copointed (f :+: g) where copoint (L1 a) = copoint a copoint (R1 a) = copoint a instance (Copointed f, Copointed g) => Copointed (f :.: g) where copoint = copoint . copoint . unComp1