    {-# LANGUAGE CPP #-}
    #if __GLASGOW_HASKELL__ >= 702
    {-# LANGUAGE Safe #-}
    #endif
    #if __GLASGOW_HASKELL__ >= 706
    {-# LANGUAGE PolyKinds #-}
    #endif
    #if __GLASGOW_HASKELL__ >= 710
    {-# LANGUAGE AutoDeriveTypeable #-}
    #endif
    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Control.Applicative.Backwards
    -- Copyright   :  (c) Russell O'Connor 2009
    -- License     :  BSD-style (see the file LICENSE)
    --
    -- Maintainer  :  R.Paterson@city.ac.uk
    -- Stability   :  experimental
    -- Portability :  portable
    --
    -- Making functors with an 'Applicative' instance that performs actions
    -- in the reverse order.
    -----------------------------------------------------------------------------

    module Control.Applicative.Backwards (
        Backwards(..),
      ) where

    import Data.Functor.Classes
    #if MIN_VERSION_base(4,12,0)
    import Data.Functor.Contravariant
    #endif

    import Prelude hiding (foldr, foldr1, foldl, foldl1, null, length)
    import Control.Applicative
    import Data.Foldable
    import Data.Traversable

    -- | The same functor, but with an 'Applicative' instance that performs
    -- actions in the reverse order.
    newtype Backwards f a = Backwards { forall {k} (f :: k -> *) (a :: k). Backwards f a -> f a
    forwards :: f a }

    instance (Eq1 f) => Eq1 (Backwards f) where
        liftEq :: forall a b.
    (a -> b -> Bool) -> Backwards f a -> Backwards f b -> Bool
    liftEq a -> b -> Bool
    eq (Backwards f a
    x) (Backwards f b
    y) = (a -> b -> Bool) -> f a -> f b -> Bool
    forall a b. (a -> b -> Bool) -> f a -> f b -> Bool
    forall (f :: * -> *) a b.
    Eq1 f =>
    (a -> b -> Bool) -> f a -> f b -> Bool
    liftEq a -> b -> Bool
    eq f a
    x f b
    y
        {-# INLINE liftEq #-}

    instance (Ord1 f) => Ord1 (Backwards f) where
        liftCompare :: forall a b.
    (a -> b -> Ordering) -> Backwards f a -> Backwards f b -> Ordering
    liftCompare a -> b -> Ordering
    comp (Backwards f a
    x) (Backwards f b
    y) = (a -> b -> Ordering) -> f a -> f b -> Ordering
    forall a b. (a -> b -> Ordering) -> f a -> f b -> Ordering
    forall (f :: * -> *) a b.
    Ord1 f =>
    (a -> b -> Ordering) -> f a -> f b -> Ordering
    liftCompare a -> b -> Ordering
    comp f a
    x f b
    y
        {-# INLINE liftCompare #-}

    instance (Read1 f) => Read1 (Backwards f) where
        liftReadsPrec :: forall a.
    (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Backwards f a)
    liftReadsPrec Int -> ReadS a
    rp ReadS [a]
    rl = (String -> ReadS (Backwards f a)) -> Int -> ReadS (Backwards f a)
    forall a. (String -> ReadS a) -> Int -> ReadS a
    readsData ((String -> ReadS (Backwards f a)) -> Int -> ReadS (Backwards f a))
    -> (String -> ReadS (Backwards f a))
    -> Int
    -> ReadS (Backwards f a)
    forall a b. (a -> b) -> a -> b
    $
            (Int -> ReadS (f a))
    -> String
    -> (f a -> Backwards f a)
    -> String
    -> ReadS (Backwards f a)
    forall a t.
    (Int -> ReadS a) -> String -> (a -> t) -> String -> ReadS t
    readsUnaryWith ((Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (f a)
    forall a. (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (f a)
    forall (f :: * -> *) a.
    Read1 f =>
    (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (f a)
    liftReadsPrec Int -> ReadS a
    rp ReadS [a]
    rl) String
    "Backwards" f a -> Backwards f a
    forall {k} (f :: k -> *) (a :: k). f a -> Backwards f a
    Backwards

    instance (Show1 f) => Show1 (Backwards f) where
        liftShowsPrec :: forall a.
    (Int -> a -> ShowS)
    -> ([a] -> ShowS) -> Int -> Backwards f a -> ShowS
    liftShowsPrec Int -> a -> ShowS
    sp [a] -> ShowS
    sl Int
    d (Backwards f a
    x) =
            (Int -> f a -> ShowS) -> String -> Int -> f a -> ShowS
    forall a. (Int -> a -> ShowS) -> String -> Int -> a -> ShowS
    showsUnaryWith ((Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> f a -> ShowS
    forall a.
    (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> f a -> ShowS
    forall (f :: * -> *) a.
    Show1 f =>
    (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> f a -> ShowS
    liftShowsPrec Int -> a -> ShowS
    sp [a] -> ShowS
    sl) String
    "Backwards" Int
    d f a
    x

    instance (Eq1 f, Eq a) => Eq (Backwards f a) where == :: Backwards f a -> Backwards f a -> Bool
    (==) = Backwards f a -> Backwards f a -> Bool
    forall (f :: * -> *) a. (Eq1 f, Eq a) => f a -> f a -> Bool
    eq1
    instance (Ord1 f, Ord a) => Ord (Backwards f a) where compare :: Backwards f a -> Backwards f a -> Ordering
    compare = Backwards f a -> Backwards f a -> Ordering
    forall (f :: * -> *) a. (Ord1 f, Ord a) => f a -> f a -> Ordering
    compare1
    instance (Read1 f, Read a) => Read (Backwards f a) where readsPrec :: Int -> ReadS (Backwards f a)
    readsPrec = Int -> ReadS (Backwards f a)
    forall (f :: * -> *) a. (Read1 f, Read a) => Int -> ReadS (f a)
    readsPrec1
    instance (Show1 f, Show a) => Show (Backwards f a) where showsPrec :: Int -> Backwards f a -> ShowS
    showsPrec = Int -> Backwards f a -> ShowS
    forall (f :: * -> *) a. (Show1 f, Show a) => Int -> f a -> ShowS
    showsPrec1

    -- | Derived instance.
    instance (Functor f) => Functor (Backwards f) where
        fmap :: forall a b. (a -> b) -> Backwards f a -> Backwards f b
    fmap a -> b
    f (Backwards f a
    a) = f b -> Backwards f b
    forall {k} (f :: k -> *) (a :: k). f a -> Backwards f a
    Backwards ((a -> b) -> f a -> f b
    forall a b. (a -> b) -> f a -> f b
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap a -> b
    f f a
    a)
        {-# INLINE fmap #-}

    -- | Apply @f@-actions in the reverse order.
    instance (Applicative f) => Applicative (Backwards f) where
        pure :: forall a. a -> Backwards f a
    pure a
    a = f a -> Backwards f a
    forall {k} (f :: k -> *) (a :: k). f a -> Backwards f a
    Backwards (a -> f a
    forall a. a -> f a
    forall (f :: * -> *) a. Applicative f => a -> f a
    pure a
    a)
        {-# INLINE pure #-}
        Backwards f (a -> b)
    f <*> :: forall a b. Backwards f (a -> b) -> Backwards f a -> Backwards f b
    <*> Backwards f a
    a = f b -> Backwards f b
    forall {k} (f :: k -> *) (a :: k). f a -> Backwards f a
    Backwards (f a
    a f a -> f (a -> b) -> f b
    forall (f :: * -> *) a b. Applicative f => f a -> f (a -> b) -> f b
    <**> f (a -> b)
    f)
        {-# INLINE (<*>) #-}

    -- | Try alternatives in the same order as @f@.
    instance (Alternative f) => Alternative (Backwards f) where
        empty :: forall a. Backwards f a
    empty = f a -> Backwards f a
    forall {k} (f :: k -> *) (a :: k). f a -> Backwards f a
    Backwards f a
    forall a. f a
    forall (f :: * -> *) a. Alternative f => f a
    empty
        {-# INLINE empty #-}
        Backwards f a
    x <|> :: forall a. Backwards f a -> Backwards f a -> Backwards f a
    <|> Backwards f a
    y = f a -> Backwards f a
    forall {k} (f :: k -> *) (a :: k). f a -> Backwards f a
    Backwards (f a
    x f a -> f a -> f a
    forall a. f a -> f a -> f a
    forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
    <|> f a
    y)
        {-# INLINE (<|>) #-}

    -- | Derived instance.
    instance (Foldable f) => Foldable (Backwards f) where
        foldMap :: forall m a. Monoid m => (a -> m) -> Backwards f a -> m
    foldMap a -> m
    f (Backwards f a
    t) = (a -> m) -> f a -> m
    forall m a. Monoid m => (a -> m) -> f a -> m
    forall (t :: * -> *) m a.
    (Foldable t, Monoid m) =>
    (a -> m) -> t a -> m
    foldMap a -> m
    f f a
    t
        {-# INLINE foldMap #-}
        foldr :: forall a b. (a -> b -> b) -> b -> Backwards f a -> b
    foldr a -> b -> b
    f b
    z (Backwards f a
    t) = (a -> b -> b) -> b -> f a -> b
    forall a b. (a -> b -> b) -> b -> f a -> b
    forall (t :: * -> *) a b.
    Foldable t =>
    (a -> b -> b) -> b -> t a -> b
    foldr a -> b -> b
    f b
    z f a
    t
        {-# INLINE foldr #-}
        foldl :: forall b a. (b -> a -> b) -> b -> Backwards f a -> b
    foldl b -> a -> b
    f b
    z (Backwards f a
    t) = (b -> a -> b) -> b -> f a -> b
    forall b a. (b -> a -> b) -> b -> f a -> b
    forall (t :: * -> *) b a.
    Foldable t =>
    (b -> a -> b) -> b -> t a -> b
    foldl b -> a -> b
    f b
    z f a
    t
        {-# INLINE foldl #-}
        foldr1 :: forall a. (a -> a -> a) -> Backwards f a -> a
    foldr1 a -> a -> a
    f (Backwards f a
    t) = (a -> a -> a) -> f a -> a
    forall a. (a -> a -> a) -> f a -> a
    forall (t :: * -> *) a. Foldable t => (a -> a -> a) -> t a -> a
    foldr1 a -> a -> a
    f f a
    t
        {-# INLINE foldr1 #-}
        foldl1 :: forall a. (a -> a -> a) -> Backwards f a -> a
    foldl1 a -> a -> a
    f (Backwards f a
    t) = (a -> a -> a) -> f a -> a
    forall a. (a -> a -> a) -> f a -> a
    forall (t :: * -> *) a. Foldable t => (a -> a -> a) -> t a -> a
    foldl1 a -> a -> a
    f f a
    t
        {-# INLINE foldl1 #-}
    #if MIN_VERSION_base(4,8,0)
        null :: forall a. Backwards f a -> Bool
    null (Backwards f a
    t) = f a -> Bool
    forall a. f a -> Bool
    forall (t :: * -> *) a. Foldable t => t a -> Bool
    null f a
    t
        length :: forall a. Backwards f a -> Int
    length (Backwards f a
    t) = f a -> Int
    forall a. f a -> Int
    forall (t :: * -> *) a. Foldable t => t a -> Int
    length f a
    t
    #endif

    -- | Derived instance.
    instance (Traversable f) => Traversable (Backwards f) where
        traverse :: forall (f :: * -> *) a b.
    Applicative f =>
    (a -> f b) -> Backwards f a -> f (Backwards f b)
    traverse a -> f b
    f (Backwards f a
    t) = (f b -> Backwards f b) -> f (f b) -> f (Backwards f b)
    forall a b. (a -> b) -> f a -> f b
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap f b -> Backwards f b
    forall {k} (f :: k -> *) (a :: k). f a -> Backwards f a
    Backwards ((a -> f b) -> f a -> f (f b)
    forall (t :: * -> *) (f :: * -> *) a b.
    (Traversable t, Applicative f) =>
    (a -> f b) -> t a -> f (t b)
    forall (f :: * -> *) a b.
    Applicative f =>
    (a -> f b) -> f a -> f (f b)
    traverse a -> f b
    f f a
    t)
        {-# INLINE traverse #-}
        sequenceA :: forall (f :: * -> *) a.
    Applicative f =>
    Backwards f (f a) -> f (Backwards f a)
    sequenceA (Backwards f (f a)
    t) = (f a -> Backwards f a) -> f (f a) -> f (Backwards f a)
    forall a b. (a -> b) -> f a -> f b
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap f a -> Backwards f a
    forall {k} (f :: k -> *) (a :: k). f a -> Backwards f a
    Backwards (f (f a) -> f (f a)
    forall (t :: * -> *) (f :: * -> *) a.
    (Traversable t, Applicative f) =>
    t (f a) -> f (t a)
    forall (f :: * -> *) a. Applicative f => f (f a) -> f (f a)
    sequenceA f (f a)
    t)
        {-# INLINE sequenceA #-}

    #if MIN_VERSION_base(4,12,0)
    -- | Derived instance.
    instance Contravariant f => Contravariant (Backwards f) where
        contramap :: forall a' a. (a' -> a) -> Backwards f a -> Backwards f a'
    contramap a' -> a
    f = f a' -> Backwards f a'
    forall {k} (f :: k -> *) (a :: k). f a -> Backwards f a
    Backwards (f a' -> Backwards f a')
    -> (Backwards f a -> f a') -> Backwards f a -> Backwards f a'
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . (a' -> a) -> f a -> f a'
    forall a' a. (a' -> a) -> f a -> f a'
    forall (f :: * -> *) a' a.
    Contravariant f =>
    (a' -> a) -> f a -> f a'
    contramap a' -> a
    f (f a -> f a') -> (Backwards f a -> f a) -> Backwards f a -> f a'
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Backwards f a -> f a
    forall {k} (f :: k -> *) (a :: k). Backwards f a -> f a
    forwards
        {-# INLINE contramap #-}
    #endif