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{-# LANGUAGE DeriveDataTypeable #-} {-# LANGUAGE DeriveGeneric #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE Safe #-}

module Data.Functor.Sum ( Sum(..), ) where

import Control.Applicative ((<|>)) import Data.Data (Data) import Data.Foldable (Foldable(foldMap)) import Data.Functor.Classes import Data.Traversable (Traversable(traverse)) import GHC.Generics (Generic, Generic1) import Text.Read (Read(..), readListDefault, readListPrecDefault)

data Sum f g a = InL (f a) | InR (g a) deriving ( Data
, Generic
, Generic1 )

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

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

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](Data.Functor.Classes.html#liftReadListPrec) = [liftReadListPrecDefault](Data.Functor.Classes.html#liftReadListPrecDefault)
[liftReadList](Data.Functor.Classes.html#liftReadList)     = [liftReadListDefault](Data.Functor.Classes.html#liftReadListDefault)

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

instance (Eq1 f, Eq1 g, Eq a) => Eq (Sum f g a) where (==) = eq1

instance (Ord1 f, Ord1 g, Ord a) => Ord (Sum f g a) where compare = compare1

instance (Read1 f, Read1 g, Read a) => Read (Sum f g a) where readPrec = readPrec1

[readListPrec](GHC.Read.html#readListPrec) = [readListPrecDefault](GHC.Read.html#readListPrecDefault)
[readList](GHC.Read.html#readList)     = [readListDefault](GHC.Read.html#readListDefault)

instance (Show1 f, Show1 g, Show a) => Show (Sum f g a) where showsPrec = showsPrec1

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)

instance (Foldable f, Foldable g) => Foldable (Sum f g) where foldMap f (InL x) = foldMap f x foldMap f (InR y) = foldMap f y

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