{-# LANGUAGE DeriveDataTypeable #-} {-# LANGUAGE DeriveGeneric #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE Safe #-} ----------------------------------------------------------------------------- -- | -- Module : Data.Functor.Sum -- Copyright : (c) Ross Paterson 2014 -- License : BSD-style (see the file LICENSE) -- -- Maintainer : libraries@haskell.org -- Stability : experimental -- Portability : portable -- -- Sums, lifted to functors. -- -- @since 4.9.0.0 ----------------------------------------------------------------------------- module Data.Functor.Sum ( Sum(..), ) where import Control.Applicative ((<|>)) import Data.Data (Data) import Data.Functor.Classes import GHC.Generics (Generic, Generic1) import Text.Read (Read(..), readListDefault, readListPrecDefault) -- | Lifted sum of functors. data Sum f g a = InL (f a) | InR (g a) deriving ( Data -- ^ @since 4.9.0.0 , Generic -- ^ @since 4.9.0.0 , Generic1 -- ^ @since 4.9.0.0 ) -- | @since 4.9.0.0 instance (Eq1 f, Eq1 g) => Eq1 (Sum f g) where liftEq eq (InL x1) (InL x2) = liftEq eq x1 x2 liftEq _ (InL _) (InR _) = False liftEq _ (InR _) (InL _) = False liftEq eq (InR y1) (InR y2) = liftEq eq y1 y2 -- | @since 4.9.0.0 instance (Ord1 f, Ord1 g) => Ord1 (Sum f g) where liftCompare comp (InL x1) (InL x2) = liftCompare comp x1 x2 liftCompare _ (InL _) (InR _) = LT liftCompare _ (InR _) (InL _) = GT liftCompare comp (InR y1) (InR y2) = liftCompare comp y1 y2 -- | @since 4.9.0.0 instance (Read1 f, Read1 g) => Read1 (Sum f g) where liftReadPrec rp rl = readData $ readUnaryWith (liftReadPrec rp rl) "InL" InL <|> readUnaryWith (liftReadPrec rp rl) "InR" InR liftReadListPrec = liftReadListPrecDefault liftReadList = liftReadListDefault -- | @since 4.9.0.0 instance (Show1 f, Show1 g) => Show1 (Sum f g) where liftShowsPrec sp sl d (InL x) = showsUnaryWith (liftShowsPrec sp sl) "InL" d x liftShowsPrec sp sl d (InR y) = showsUnaryWith (liftShowsPrec sp sl) "InR" d y -- | @since 4.9.0.0 instance (Eq1 f, Eq1 g, Eq a) => Eq (Sum f g a) where (==) = eq1 -- | @since 4.9.0.0 instance (Ord1 f, Ord1 g, Ord a) => Ord (Sum f g a) where compare = compare1 -- | @since 4.9.0.0 instance (Read1 f, Read1 g, Read a) => Read (Sum f g a) where readPrec = readPrec1 readListPrec = readListPrecDefault readList = readListDefault -- | @since 4.9.0.0 instance (Show1 f, Show1 g, Show a) => Show (Sum f g a) where showsPrec = showsPrec1 -- | @since 4.9.0.0 instance (Functor f, Functor g) => Functor (Sum f g) where fmap f (InL x) = InL (fmap f x) fmap f (InR y) = InR (fmap f y) a <$ (InL x) = InL (a <$ x) a <$ (InR y) = InR (a <$ y) -- | @since 4.9.0.0 instance (Foldable f, Foldable g) => Foldable (Sum f g) where foldMap f (InL x) = foldMap f x foldMap f (InR y) = foldMap f y -- | @since 4.9.0.0 instance (Traversable f, Traversable g) => Traversable (Sum f g) where traverse f (InL x) = InL <$> traverse f x traverse f (InR y) = InR <$> traverse f y