    {-# LANGUAGE CPP #-}
    #if __GLASGOW_HASKELL__ >= 702
    {-# LANGUAGE Safe #-}
    #endif
    #if __GLASGOW_HASKELL__ >= 706
    {-# LANGUAGE PolyKinds #-}
    #endif
    #if __GLASGOW_HASKELL__ >= 710
    {-# LANGUAGE AutoDeriveTypeable #-}
    #endif
    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Data.Functor.Reverse
    -- 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 whose elements are notionally in the reverse order
    -- from the original functor.
    -----------------------------------------------------------------------------

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

    import Control.Applicative.Backwards
    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 Control.Monad
    #if MIN_VERSION_base(4,9,0)
    import qualified Control.Monad.Fail as Fail
    #endif
    import Data.Foldable
    import Data.Traversable
    import Data.Monoid

    -- | The same functor, but with 'Foldable' and 'Traversable' instances
    -- that process the elements in the reverse order.
    newtype Reverse f a = Reverse { forall {k} (f :: k -> *) (a :: k). Reverse f a -> f a
    getReverse :: f a }

    instance (Eq1 f) => Eq1 (Reverse f) where
        liftEq :: forall a b. (a -> b -> Bool) -> Reverse f a -> Reverse f b -> Bool
    liftEq a -> b -> Bool
    eq (Reverse f a
    x) (Reverse f b
    y) = 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 (Reverse f) where
        liftCompare :: forall a b.
    (a -> b -> Ordering) -> Reverse f a -> Reverse f b -> Ordering
    liftCompare a -> b -> Ordering
    comp (Reverse f a
    x) (Reverse f b
    y) = 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 (Reverse f) where
        liftReadsPrec :: forall a.
    (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Reverse f a)
    liftReadsPrec Int -> ReadS a
    rp ReadS [a]
    rl = forall a. (String -> ReadS a) -> Int -> ReadS a
    readsData forall a b. (a -> b) -> a -> b
    $
            forall a t.
    (Int -> ReadS a) -> String -> (a -> t) -> String -> ReadS t
    readsUnaryWith (forall (f :: * -> *) a.
    Read1 f =>
    (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (f a)
    liftReadsPrec Int -> ReadS a
    rp ReadS [a]
    rl) String
    "Reverse" forall {k} (f :: k -> *) (a :: k). f a -> Reverse f a
    Reverse

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

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

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

    -- | Derived instance.
    instance (Applicative f) => Applicative (Reverse f) where
        pure :: forall a. a -> Reverse f a
    pure a
    a = forall {k} (f :: k -> *) (a :: k). f a -> Reverse f a
    Reverse (forall (f :: * -> *) a. Applicative f => a -> f a
    pure a
    a)
        {-# INLINE pure #-}
        Reverse f (a -> b)
    f <*> :: forall a b. Reverse f (a -> b) -> Reverse f a -> Reverse f b
    <*> Reverse f a
    a = forall {k} (f :: k -> *) (a :: k). f a -> Reverse f a
    Reverse (f (a -> b)
    f forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
    <*> f a
    a)
        {-# INLINE (<*>) #-}

    -- | Derived instance.
    instance (Alternative f) => Alternative (Reverse f) where
        empty :: forall a. Reverse f a
    empty = forall {k} (f :: k -> *) (a :: k). f a -> Reverse f a
    Reverse forall (f :: * -> *) a. Alternative f => f a
    empty
        {-# INLINE empty #-}
        Reverse f a
    x <|> :: forall a. Reverse f a -> Reverse f a -> Reverse f a
    <|> Reverse f a
    y = forall {k} (f :: k -> *) (a :: k). f a -> Reverse f a
    Reverse (f a
    x forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
    <|> f a
    y)
        {-# INLINE (<|>) #-}

    -- | Derived instance.
    instance (Monad m) => Monad (Reverse m) where
    #if !(MIN_VERSION_base(4,8,0))
        return a = Reverse (return a)
        {-# INLINE return #-}
    #endif
        Reverse m a
    m >>= :: forall a b. Reverse m a -> (a -> Reverse m b) -> Reverse m b
    >>= a -> Reverse m b
    f = forall {k} (f :: k -> *) (a :: k). f a -> Reverse f a
    Reverse (forall {k} (f :: k -> *) (a :: k). Reverse f a -> f a
    getReverse Reverse m a
    m forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
    >>= forall {k} (f :: k -> *) (a :: k). Reverse f a -> f a
    getReverse forall b c a. (b -> c) -> (a -> b) -> a -> c
    . a -> Reverse m b
    f)
        {-# INLINE (>>=) #-}
    #if !(MIN_VERSION_base(4,13,0))
        fail msg = Reverse (fail msg)
        {-# INLINE fail #-}
    #endif

    #if MIN_VERSION_base(4,9,0)
    instance (Fail.MonadFail m) => Fail.MonadFail (Reverse m) where
        fail :: forall a. String -> Reverse m a
    fail String
    msg = forall {k} (f :: k -> *) (a :: k). f a -> Reverse f a
    Reverse (forall (m :: * -> *) a. MonadFail m => String -> m a
    Fail.fail String
    msg)
        {-# INLINE fail #-}
    #endif

    -- | Derived instance.
    instance (MonadPlus m) => MonadPlus (Reverse m) where
        mzero :: forall a. Reverse m a
    mzero = forall {k} (f :: k -> *) (a :: k). f a -> Reverse f a
    Reverse forall (m :: * -> *) a. MonadPlus m => m a
    mzero
        {-# INLINE mzero #-}
        Reverse m a
    x mplus :: forall a. Reverse m a -> Reverse m a -> Reverse m a
    `mplus` Reverse m a
    y = forall {k} (f :: k -> *) (a :: k). f a -> Reverse f a
    Reverse (m a
    x forall (m :: * -> *) a. MonadPlus m => m a -> m a -> m a
    `mplus` m a
    y)
        {-# INLINE mplus #-}

    -- | Fold from right to left.
    instance (Foldable f) => Foldable (Reverse f) where
        foldMap :: forall m a. Monoid m => (a -> m) -> Reverse f a -> m
    foldMap a -> m
    f (Reverse f a
    t) = forall a. Dual a -> a
    getDual (forall (t :: * -> *) m a.
    (Foldable t, Monoid m) =>
    (a -> m) -> t a -> m
    foldMap (forall a. a -> Dual a
    Dual forall b c a. (b -> c) -> (a -> b) -> a -> c
    . a -> m
    f) f a
    t)
        {-# INLINE foldMap #-}
        foldr :: forall a b. (a -> b -> b) -> b -> Reverse f a -> b
    foldr a -> b -> b
    f b
    z (Reverse f a
    t) = forall (t :: * -> *) b a.
    Foldable t =>
    (b -> a -> b) -> b -> t a -> b
    foldl (forall a b c. (a -> b -> c) -> b -> a -> c
    flip a -> b -> b
    f) b
    z f a
    t
        {-# INLINE foldr #-}
        foldl :: forall b a. (b -> a -> b) -> b -> Reverse f a -> b
    foldl b -> a -> b
    f b
    z (Reverse f a
    t) = forall (t :: * -> *) a b.
    Foldable t =>
    (a -> b -> b) -> b -> t a -> b
    foldr (forall a b c. (a -> b -> c) -> b -> a -> c
    flip b -> a -> b
    f) b
    z f a
    t
        {-# INLINE foldl #-}
        foldr1 :: forall a. (a -> a -> a) -> Reverse f a -> a
    foldr1 a -> a -> a
    f (Reverse f a
    t) = forall (t :: * -> *) a. Foldable t => (a -> a -> a) -> t a -> a
    foldl1 (forall a b c. (a -> b -> c) -> b -> a -> c
    flip a -> a -> a
    f) f a
    t
        {-# INLINE foldr1 #-}
        foldl1 :: forall a. (a -> a -> a) -> Reverse f a -> a
    foldl1 a -> a -> a
    f (Reverse f a
    t) = forall (t :: * -> *) a. Foldable t => (a -> a -> a) -> t a -> a
    foldr1 (forall a b c. (a -> b -> c) -> b -> a -> c
    flip a -> a -> a
    f) f a
    t
        {-# INLINE foldl1 #-}
    #if MIN_VERSION_base(4,8,0)
        null :: forall a. Reverse f a -> Bool
    null (Reverse f a
    t) = forall (t :: * -> *) a. Foldable t => t a -> Bool
    null f a
    t
        length :: forall a. Reverse f a -> Int
    length (Reverse f a
    t) = forall (t :: * -> *) a. Foldable t => t a -> Int
    length f a
    t
    #endif

    -- | Traverse from right to left.
    instance (Traversable f) => Traversable (Reverse f) where
        traverse :: forall (f :: * -> *) a b.
    Applicative f =>
    (a -> f b) -> Reverse f a -> f (Reverse f b)
    traverse a -> f b
    f (Reverse f a
    t) =
            forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap forall {k} (f :: k -> *) (a :: k). f a -> Reverse f a
    Reverse forall b c a. (b -> c) -> (a -> b) -> a -> c
    . forall {k} (f :: k -> *) (a :: k). Backwards f a -> f a
    forwards forall a b. (a -> b) -> a -> b
    $ forall (t :: * -> *) (f :: * -> *) a b.
    (Traversable t, Applicative f) =>
    (a -> f b) -> t a -> f (t b)
    traverse (forall {k} (f :: k -> *) (a :: k). f a -> Backwards f a
    Backwards forall b c a. (b -> c) -> (a -> b) -> a -> c
    . a -> f b
    f) f a
    t
        {-# INLINE traverse #-}

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