module Data.Pointed where import Control.Arrow import Control.Applicative import Control.Concurrent.STM import Data.Default import Data.Monoid as Monoid import Data.Semigroup as Semigroup import Data.Functor.Identity import Data.Sequence (Seq) import qualified Data.Sequence as Seq import Data.Tree (Tree(..)) import Data.Set (Set) import qualified Data.Set as Set import Data.Functor.Constant import qualified Data.Functor.Product as Functor import Data.Functor.Compose import Control.Monad.Trans.Cont import Control.Monad.Trans.Error import Control.Monad.Trans.List import Control.Monad.Trans.Maybe import Control.Monad.Trans.Identity import qualified Control.Monad.Trans.RWS.Lazy as Lazy import qualified Control.Monad.Trans.RWS.Strict as Strict import qualified Control.Monad.Trans.Writer.Lazy as Lazy import qualified Control.Monad.Trans.Writer.Strict as Strict import qualified Control.Monad.Trans.State.Lazy as Lazy import qualified Control.Monad.Trans.State.Strict as Strict import Data.Semigroupoid.Static -- | 'Pointed' does not require a 'Functor', as the only relationship -- between 'point' and 'fmap' is given by a free theorem. class Pointed p where point :: a -> p a instance Pointed [] where point a = [a] instance Pointed Maybe where point = Just instance Pointed (Either a) where point = Right instance Pointed IO where point = return instance Pointed STM where point = return instance Pointed Tree where point a = Node a [] instance Pointed ZipList where point = pure instance Pointed Identity where point = Identity instance Pointed ((->)e) where point = const instance Default e => Pointed ((,)e) where point = (,) def instance Monad m => Pointed (WrappedMonad m) where point = WrapMonad . return instance Default m => Pointed (Const m) where point _ = Const def instance Arrow a => Pointed (WrappedArrow a b) where point = pure instance Pointed Dual where point = Dual instance Pointed Endo where point = Endo . const instance Pointed Sum where point = Sum instance Pointed Monoid.Product where point = Monoid.Product instance Pointed Monoid.First where point = Monoid.First . Just instance Pointed Monoid.Last where point = Monoid.Last . Just instance Pointed Semigroup.First where point = Semigroup.First instance Pointed Semigroup.Last where point = Semigroup.Last instance Pointed Semigroup.Max where point = Semigroup.Max instance Pointed Semigroup.Min where point = Semigroup.Min instance Pointed Seq where point = Seq.singleton instance Pointed Set where point = Set.singleton instance (Pointed p, Pointed q) => Pointed (Compose p q) where point = Compose . point . point instance (Pointed p, Pointed q) => Pointed (Functor.Product p q) where point a = Functor.Pair (point a) (point a) instance Default m => Pointed (Constant m) where point _ = Constant def instance Pointed (ContT r m) where point a = ContT ($ a) instance Pointed m => Pointed (ErrorT e m) where point = ErrorT . point . Right instance Pointed m => Pointed (IdentityT m) where point = IdentityT . point instance Pointed m => Pointed (ListT m) where point = ListT . point . point instance Pointed m => Pointed (MaybeT m) where point = MaybeT . point . point instance (Default w, Pointed m) => Pointed (Lazy.RWST r w s m) where point a = Lazy.RWST $ \_ s -> point (a, s, def) instance (Default w, Pointed m) => Pointed (Strict.RWST r w s m) where point a = Strict.RWST $ \_ s -> point (a, s, def) instance (Default w, Pointed m) => Pointed (Lazy.WriterT w m) where point a = Lazy.WriterT $ point (a, def) instance (Default w, Pointed m) => Pointed (Strict.WriterT w m) where point a = Strict.WriterT $ point (a, def) instance Pointed m => Pointed (Lazy.StateT s m) where point a = Lazy.StateT $ \s -> point (a, s) instance Pointed m => Pointed (Strict.StateT s m) where point a = Strict.StateT $ \s -> point (a, s) instance Pointed m => Pointed (Static m a) where point = Static . point . const