    -- Strict counterparts to common data structures,
    -- e.g. tuples, lists, maybes, etc.
    --
    -- Import this module qualified as Strict.

    {-# LANGUAGE DeriveDataTypeable #-}
    {-# LANGUAGE DeriveTraversable #-}

    module GHC.Data.Strict (
        Maybe(Nothing, Just),
        fromMaybe,
        Pair(And),

        -- Not used at the moment:
        --
        -- Either(Left, Right),
        -- List(Nil, Cons),
      ) where

    import GHC.Prelude hiding (Maybe(..), Either(..))
    import Control.Applicative
    import Data.Semigroup
    import Data.Data

    data Maybe a = Nothing | Just !a
      deriving (Maybe a -> Maybe a -> Bool
    (Maybe a -> Maybe a -> Bool)
    -> (Maybe a -> Maybe a -> Bool) -> Eq (Maybe a)
    forall a. Eq a => Maybe a -> Maybe a -> Bool
    forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
    $c== :: forall a. Eq a => Maybe a -> Maybe a -> Bool
    == :: Maybe a -> Maybe a -> Bool
    $c/= :: forall a. Eq a => Maybe a -> Maybe a -> Bool
    /= :: Maybe a -> Maybe a -> Bool
    Eq, Eq (Maybe a)
    Eq (Maybe a)
    -> (Maybe a -> Maybe a -> Ordering)
    -> (Maybe a -> Maybe a -> Bool)
    -> (Maybe a -> Maybe a -> Bool)
    -> (Maybe a -> Maybe a -> Bool)
    -> (Maybe a -> Maybe a -> Bool)
    -> (Maybe a -> Maybe a -> Maybe a)
    -> (Maybe a -> Maybe a -> Maybe a)
    -> Ord (Maybe a)
    Maybe a -> Maybe a -> Bool
    Maybe a -> Maybe a -> Ordering
    Maybe a -> Maybe a -> Maybe a
    forall a.
    Eq a
    -> (a -> a -> Ordering)
    -> (a -> a -> Bool)
    -> (a -> a -> Bool)
    -> (a -> a -> Bool)
    -> (a -> a -> Bool)
    -> (a -> a -> a)
    -> (a -> a -> a)
    -> Ord a
    forall {a}. Ord a => Eq (Maybe a)
    forall a. Ord a => Maybe a -> Maybe a -> Bool
    forall a. Ord a => Maybe a -> Maybe a -> Ordering
    forall a. Ord a => Maybe a -> Maybe a -> Maybe a
    $ccompare :: forall a. Ord a => Maybe a -> Maybe a -> Ordering
    compare :: Maybe a -> Maybe a -> Ordering
    $c< :: forall a. Ord a => Maybe a -> Maybe a -> Bool
    < :: Maybe a -> Maybe a -> Bool
    $c<= :: forall a. Ord a => Maybe a -> Maybe a -> Bool
    <= :: Maybe a -> Maybe a -> Bool
    $c> :: forall a. Ord a => Maybe a -> Maybe a -> Bool
    > :: Maybe a -> Maybe a -> Bool
    $c>= :: forall a. Ord a => Maybe a -> Maybe a -> Bool
    >= :: Maybe a -> Maybe a -> Bool
    $cmax :: forall a. Ord a => Maybe a -> Maybe a -> Maybe a
    max :: Maybe a -> Maybe a -> Maybe a
    $cmin :: forall a. Ord a => Maybe a -> Maybe a -> Maybe a
    min :: Maybe a -> Maybe a -> Maybe a
    Ord, Int -> Maybe a -> ShowS
    [Maybe a] -> ShowS
    Maybe a -> String
    (Int -> Maybe a -> ShowS)
    -> (Maybe a -> String) -> ([Maybe a] -> ShowS) -> Show (Maybe a)
    forall a. Show a => Int -> Maybe a -> ShowS
    forall a. Show a => [Maybe a] -> ShowS
    forall a. Show a => Maybe a -> String
    forall a.
    (Int -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
    $cshowsPrec :: forall a. Show a => Int -> Maybe a -> ShowS
    showsPrec :: Int -> Maybe a -> ShowS
    $cshow :: forall a. Show a => Maybe a -> String
    show :: Maybe a -> String
    $cshowList :: forall a. Show a => [Maybe a] -> ShowS
    showList :: [Maybe a] -> ShowS
    Show, (forall a b. (a -> b) -> Maybe a -> Maybe b)
    -> (forall a b. a -> Maybe b -> Maybe a) -> Functor Maybe
    forall a b. a -> Maybe b -> Maybe a
    forall a b. (a -> b) -> Maybe a -> Maybe b
    forall (f :: * -> *).
    (forall a b. (a -> b) -> f a -> f b)
    -> (forall a b. a -> f b -> f a) -> Functor f
    $cfmap :: forall a b. (a -> b) -> Maybe a -> Maybe b
    fmap :: forall a b. (a -> b) -> Maybe a -> Maybe b
    $c<$ :: forall a b. a -> Maybe b -> Maybe a
    <$ :: forall a b. a -> Maybe b -> Maybe a
    Functor, (forall m. Monoid m => Maybe m -> m)
    -> (forall m a. Monoid m => (a -> m) -> Maybe a -> m)
    -> (forall m a. Monoid m => (a -> m) -> Maybe a -> m)
    -> (forall a b. (a -> b -> b) -> b -> Maybe a -> b)
    -> (forall a b. (a -> b -> b) -> b -> Maybe a -> b)
    -> (forall b a. (b -> a -> b) -> b -> Maybe a -> b)
    -> (forall b a. (b -> a -> b) -> b -> Maybe a -> b)
    -> (forall a. (a -> a -> a) -> Maybe a -> a)
    -> (forall a. (a -> a -> a) -> Maybe a -> a)
    -> (forall a. Maybe a -> [a])
    -> (forall a. Maybe a -> Bool)
    -> (forall a. Maybe a -> Int)
    -> (forall a. Eq a => a -> Maybe a -> Bool)
    -> (forall a. Ord a => Maybe a -> a)
    -> (forall a. Ord a => Maybe a -> a)
    -> (forall a. Num a => Maybe a -> a)
    -> (forall a. Num a => Maybe a -> a)
    -> Foldable Maybe
    forall a. Eq a => a -> Maybe a -> Bool
    forall a. Num a => Maybe a -> a
    forall a. Ord a => Maybe a -> a
    forall m. Monoid m => Maybe m -> m
    forall a. Maybe a -> Bool
    forall a. Maybe a -> Int
    forall a. Maybe a -> [a]
    forall a. (a -> a -> a) -> Maybe a -> a
    forall m a. Monoid m => (a -> m) -> Maybe a -> m
    forall b a. (b -> a -> b) -> b -> Maybe a -> b
    forall a b. (a -> b -> b) -> b -> Maybe a -> b
    forall (t :: * -> *).
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    -> (forall m a. Monoid m => (a -> m) -> t a -> m)
    -> (forall m a. Monoid m => (a -> m) -> t a -> m)
    -> (forall a b. (a -> b -> b) -> b -> t a -> b)
    -> (forall a b. (a -> b -> b) -> b -> t a -> b)
    -> (forall b a. (b -> a -> b) -> b -> t a -> b)
    -> (forall b a. (b -> a -> b) -> b -> t a -> b)
    -> (forall a. (a -> a -> a) -> t a -> a)
    -> (forall a. (a -> a -> a) -> t a -> a)
    -> (forall a. t a -> [a])
    -> (forall a. t a -> Bool)
    -> (forall a. t a -> Int)
    -> (forall a. Eq a => a -> t a -> Bool)
    -> (forall a. Ord a => t a -> a)
    -> (forall a. Ord a => t a -> a)
    -> (forall a. Num a => t a -> a)
    -> (forall a. Num a => t a -> a)
    -> Foldable t
    $cfold :: forall m. Monoid m => Maybe m -> m
    fold :: forall m. Monoid m => Maybe m -> m
    $cfoldMap :: forall m a. Monoid m => (a -> m) -> Maybe a -> m
    foldMap :: forall m a. Monoid m => (a -> m) -> Maybe a -> m
    $cfoldMap' :: forall m a. Monoid m => (a -> m) -> Maybe a -> m
    foldMap' :: forall m a. Monoid m => (a -> m) -> Maybe a -> m
    $cfoldr :: forall a b. (a -> b -> b) -> b -> Maybe a -> b
    foldr :: forall a b. (a -> b -> b) -> b -> Maybe a -> b
    $cfoldr' :: forall a b. (a -> b -> b) -> b -> Maybe a -> b
    foldr' :: forall a b. (a -> b -> b) -> b -> Maybe a -> b
    $cfoldl :: forall b a. (b -> a -> b) -> b -> Maybe a -> b
    foldl :: forall b a. (b -> a -> b) -> b -> Maybe a -> b
    $cfoldl' :: forall b a. (b -> a -> b) -> b -> Maybe a -> b
    foldl' :: forall b a. (b -> a -> b) -> b -> Maybe a -> b
    $cfoldr1 :: forall a. (a -> a -> a) -> Maybe a -> a
    foldr1 :: forall a. (a -> a -> a) -> Maybe a -> a
    $cfoldl1 :: forall a. (a -> a -> a) -> Maybe a -> a
    foldl1 :: forall a. (a -> a -> a) -> Maybe a -> a
    $ctoList :: forall a. Maybe a -> [a]
    toList :: forall a. Maybe a -> [a]
    $cnull :: forall a. Maybe a -> Bool
    null :: forall a. Maybe a -> Bool
    $clength :: forall a. Maybe a -> Int
    length :: forall a. Maybe a -> Int
    $celem :: forall a. Eq a => a -> Maybe a -> Bool
    elem :: forall a. Eq a => a -> Maybe a -> Bool
    $cmaximum :: forall a. Ord a => Maybe a -> a
    maximum :: forall a. Ord a => Maybe a -> a
    $cminimum :: forall a. Ord a => Maybe a -> a
    minimum :: forall a. Ord a => Maybe a -> a
    $csum :: forall a. Num a => Maybe a -> a
    sum :: forall a. Num a => Maybe a -> a
    $cproduct :: forall a. Num a => Maybe a -> a
    product :: forall a. Num a => Maybe a -> a
    Foldable, Functor Maybe
    Foldable Maybe
    Functor Maybe
    -> Foldable Maybe
    -> (forall (f :: * -> *) a b.
        Applicative f =>
        (a -> f b) -> Maybe a -> f (Maybe b))
    -> (forall (f :: * -> *) a.
        Applicative f =>
        Maybe (f a) -> f (Maybe a))
    -> (forall (m :: * -> *) a b.
        Monad m =>
        (a -> m b) -> Maybe a -> m (Maybe b))
    -> (forall (m :: * -> *) a. Monad m => Maybe (m a) -> m (Maybe a))
    -> Traversable Maybe
    forall (t :: * -> *).
    Functor t
    -> Foldable t
    -> (forall (f :: * -> *) a b.
        Applicative f =>
        (a -> f b) -> t a -> f (t b))
    -> (forall (f :: * -> *) a. Applicative f => t (f a) -> f (t a))
    -> (forall (m :: * -> *) a b.
        Monad m =>
        (a -> m b) -> t a -> m (t b))
    -> (forall (m :: * -> *) a. Monad m => t (m a) -> m (t a))
    -> Traversable t
    forall (m :: * -> *) a. Monad m => Maybe (m a) -> m (Maybe a)
    forall (f :: * -> *) a. Applicative f => Maybe (f a) -> f (Maybe a)
    forall (m :: * -> *) a b.
    Monad m =>
    (a -> m b) -> Maybe a -> m (Maybe b)
    forall (f :: * -> *) a b.
    Applicative f =>
    (a -> f b) -> Maybe a -> f (Maybe b)
    $ctraverse :: forall (f :: * -> *) a b.
    Applicative f =>
    (a -> f b) -> Maybe a -> f (Maybe b)
    traverse :: forall (f :: * -> *) a b.
    Applicative f =>
    (a -> f b) -> Maybe a -> f (Maybe b)
    $csequenceA :: forall (f :: * -> *) a. Applicative f => Maybe (f a) -> f (Maybe a)
    sequenceA :: forall (f :: * -> *) a. Applicative f => Maybe (f a) -> f (Maybe a)
    $cmapM :: forall (m :: * -> *) a b.
    Monad m =>
    (a -> m b) -> Maybe a -> m (Maybe b)
    mapM :: forall (m :: * -> *) a b.
    Monad m =>
    (a -> m b) -> Maybe a -> m (Maybe b)
    $csequence :: forall (m :: * -> *) a. Monad m => Maybe (m a) -> m (Maybe a)
    sequence :: forall (m :: * -> *) a. Monad m => Maybe (m a) -> m (Maybe a)
    Traversable, Typeable (Maybe a)
    Typeable (Maybe a)
    -> (forall (c :: * -> *).
        (forall d b. Data d => c (d -> b) -> d -> c b)
        -> (forall g. g -> c g) -> Maybe a -> c (Maybe a))
    -> (forall (c :: * -> *).
        (forall b r. Data b => c (b -> r) -> c r)
        -> (forall r. r -> c r) -> Constr -> c (Maybe a))
    -> (Maybe a -> Constr)
    -> (Maybe a -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
        Typeable t =>
        (forall d. Data d => c (t d)) -> Maybe (c (Maybe a)))
    -> (forall (t :: * -> * -> *) (c :: * -> *).
        Typeable t =>
        (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Maybe a)))
    -> ((forall b. Data b => b -> b) -> Maybe a -> Maybe a)
    -> (forall r r'.
        (r -> r' -> r)
        -> r -> (forall d. Data d => d -> r') -> Maybe a -> r)
    -> (forall r r'.
        (r' -> r -> r)
        -> r -> (forall d. Data d => d -> r') -> Maybe a -> r)
    -> (forall u. (forall d. Data d => d -> u) -> Maybe a -> [u])
    -> (forall u. Int -> (forall d. Data d => d -> u) -> Maybe a -> u)
    -> (forall (m :: * -> *).
        Monad m =>
        (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a))
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a))
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a))
    -> Data (Maybe a)
    Maybe a -> Constr
    Maybe a -> DataType
    (forall b. Data b => b -> b) -> Maybe a -> Maybe a
    forall {a}. Data a => Typeable (Maybe a)
    forall a. Data a => Maybe a -> Constr
    forall a. Data a => Maybe a -> DataType
    forall a.
    Data a =>
    (forall b. Data b => b -> b) -> Maybe a -> Maybe a
    forall a u.
    Data a =>
    Int -> (forall d. Data d => d -> u) -> Maybe a -> u
    forall a u.
    Data a =>
    (forall d. Data d => d -> u) -> Maybe a -> [u]
    forall a r r'.
    Data a =>
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> Maybe a -> r
    forall a r r'.
    Data a =>
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> Maybe a -> r
    forall a (m :: * -> *).
    (Data a, Monad m) =>
    (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a)
    forall a (m :: * -> *).
    (Data a, MonadPlus m) =>
    (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a)
    forall a (c :: * -> *).
    Data a =>
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c (Maybe a)
    forall a (c :: * -> *).
    Data a =>
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> Maybe a -> c (Maybe a)
    forall a (t :: * -> *) (c :: * -> *).
    (Data a, Typeable t) =>
    (forall d. Data d => c (t d)) -> Maybe (c (Maybe a))
    forall a (t :: * -> * -> *) (c :: * -> *).
    (Data a, Typeable t) =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Maybe a))
    forall a.
    Typeable a
    -> (forall (c :: * -> *).
        (forall d b. Data d => c (d -> b) -> d -> c b)
        -> (forall g. g -> c g) -> a -> c a)
    -> (forall (c :: * -> *).
        (forall b r. Data b => c (b -> r) -> c r)
        -> (forall r. r -> c r) -> Constr -> c a)
    -> (a -> Constr)
    -> (a -> DataType)
    -> (forall (t :: * -> *) (c :: * -> *).
        Typeable t =>
        (forall d. Data d => c (t d)) -> Maybe (c a))
    -> (forall (t :: * -> * -> *) (c :: * -> *).
        Typeable t =>
        (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c a))
    -> ((forall b. Data b => b -> b) -> a -> a)
    -> (forall r r'.
        (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> a -> r)
    -> (forall r r'.
        (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> a -> r)
    -> (forall u. (forall d. Data d => d -> u) -> a -> [u])
    -> (forall u. Int -> (forall d. Data d => d -> u) -> a -> u)
    -> (forall (m :: * -> *).
        Monad m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> (forall (m :: * -> *).
        MonadPlus m =>
        (forall d. Data d => d -> m d) -> a -> m a)
    -> Data a
    forall u. Int -> (forall d. Data d => d -> u) -> Maybe a -> u
    forall u. (forall d. Data d => d -> u) -> Maybe a -> [u]
    forall r r'.
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> Maybe a -> r
    forall r r'.
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> Maybe a -> r
    forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a)
    forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a)
    forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c (Maybe a)
    forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> Maybe a -> c (Maybe a)
    forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c (Maybe a))
    forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Maybe a))
    $cgfoldl :: forall a (c :: * -> *).
    Data a =>
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> Maybe a -> c (Maybe a)
    gfoldl :: forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> Maybe a -> c (Maybe a)
    $cgunfold :: forall a (c :: * -> *).
    Data a =>
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c (Maybe a)
    gunfold :: forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c (Maybe a)
    $ctoConstr :: forall a. Data a => Maybe a -> Constr
    toConstr :: Maybe a -> Constr
    $cdataTypeOf :: forall a. Data a => Maybe a -> DataType
    dataTypeOf :: Maybe a -> DataType
    $cdataCast1 :: forall a (t :: * -> *) (c :: * -> *).
    (Data a, Typeable t) =>
    (forall d. Data d => c (t d)) -> Maybe (c (Maybe a))
    dataCast1 :: forall (t :: * -> *) (c :: * -> *).
    Typeable t =>
    (forall d. Data d => c (t d)) -> Maybe (c (Maybe a))
    $cdataCast2 :: forall a (t :: * -> * -> *) (c :: * -> *).
    (Data a, Typeable t) =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Maybe a))
    dataCast2 :: forall (t :: * -> * -> *) (c :: * -> *).
    Typeable t =>
    (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Maybe a))
    $cgmapT :: forall a.
    Data a =>
    (forall b. Data b => b -> b) -> Maybe a -> Maybe a
    gmapT :: (forall b. Data b => b -> b) -> Maybe a -> Maybe a
    $cgmapQl :: forall a r r'.
    Data a =>
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> Maybe a -> r
    gmapQl :: forall r r'.
    (r -> r' -> r)
    -> r -> (forall d. Data d => d -> r') -> Maybe a -> r
    $cgmapQr :: forall a r r'.
    Data a =>
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> Maybe a -> r
    gmapQr :: forall r r'.
    (r' -> r -> r)
    -> r -> (forall d. Data d => d -> r') -> Maybe a -> r
    $cgmapQ :: forall a u.
    Data a =>
    (forall d. Data d => d -> u) -> Maybe a -> [u]
    gmapQ :: forall u. (forall d. Data d => d -> u) -> Maybe a -> [u]
    $cgmapQi :: forall a u.
    Data a =>
    Int -> (forall d. Data d => d -> u) -> Maybe a -> u
    gmapQi :: forall u. Int -> (forall d. Data d => d -> u) -> Maybe a -> u
    $cgmapM :: forall a (m :: * -> *).
    (Data a, Monad m) =>
    (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a)
    gmapM :: forall (m :: * -> *).
    Monad m =>
    (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a)
    $cgmapMp :: forall a (m :: * -> *).
    (Data a, MonadPlus m) =>
    (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a)
    gmapMp :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a)
    $cgmapMo :: forall a (m :: * -> *).
    (Data a, MonadPlus m) =>
    (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a)
    gmapMo :: forall (m :: * -> *).
    MonadPlus m =>
    (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a)
    Data)

    fromMaybe :: a -> Maybe a -> a
    fromMaybe :: forall a. a -> Maybe a -> a
    fromMaybe a
    d Maybe a
    Nothing = a
    d
    fromMaybe a
    _ (Just a
    x) = a
    x

    apMaybe :: Maybe (a -> b) -> Maybe a -> Maybe b
    apMaybe :: forall a b. Maybe (a -> b) -> Maybe a -> Maybe b
    apMaybe (Just a -> b
    f) (Just a
    x) = b -> Maybe b
    forall a. a -> Maybe a
    Just (a -> b
    f a
    x)
    apMaybe Maybe (a -> b)
    _ Maybe a
    _ = Maybe b
    forall a. Maybe a
    Nothing

    altMaybe :: Maybe a -> Maybe a -> Maybe a
    altMaybe :: forall a. Maybe a -> Maybe a -> Maybe a
    altMaybe Maybe a
    Nothing Maybe a
    r = Maybe a
    r
    altMaybe Maybe a
    l Maybe a
    _ = Maybe a
    l

    instance Semigroup a => Semigroup (Maybe a) where
      Maybe a
    Nothing <> :: Maybe a -> Maybe a -> Maybe a
    <> Maybe a
    b       = Maybe a
    b
      Maybe a
    a       <> Maybe a
    Nothing = Maybe a
    a
      Just a
    a  <> Just a
    b  = a -> Maybe a
    forall a. a -> Maybe a
    Just (a
    a a -> a -> a
    forall a. Semigroup a => a -> a -> a
    <> a
    b)

    instance Semigroup a => Monoid (Maybe a) where
      mempty :: Maybe a
    mempty = Maybe a
    forall a. Maybe a
    Nothing

    instance Applicative Maybe where
      pure :: forall a. a -> Maybe a
    pure = a -> Maybe a
    forall a. a -> Maybe a
    Just
      <*> :: forall a b. Maybe (a -> b) -> Maybe a -> Maybe b
    (<*>) = Maybe (a -> b) -> Maybe a -> Maybe b
    forall a b. Maybe (a -> b) -> Maybe a -> Maybe b
    apMaybe

    instance Alternative Maybe where
      empty :: forall a. Maybe a
    empty = Maybe a
    forall a. Maybe a
    Nothing
      <|> :: forall a. Maybe a -> Maybe a -> Maybe a
    (<|>) = Maybe a -> Maybe a -> Maybe a
    forall a. Maybe a -> Maybe a -> Maybe a
    altMaybe

    data Pair a b = !a `And` !b
      deriving (Pair a b -> Pair a b -> Bool
    (Pair a b -> Pair a b -> Bool)
    -> (Pair a b -> Pair a b -> Bool) -> Eq (Pair a b)
    forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
    forall a b. (Eq a, Eq b) => Pair a b -> Pair a b -> Bool
    $c== :: forall a b. (Eq a, Eq b) => Pair a b -> Pair a b -> Bool
    == :: Pair a b -> Pair a b -> Bool
    $c/= :: forall a b. (Eq a, Eq b) => Pair a b -> Pair a b -> Bool
    /= :: Pair a b -> Pair a b -> Bool
    Eq, Eq (Pair a b)
    Eq (Pair a b)
    -> (Pair a b -> Pair a b -> Ordering)
    -> (Pair a b -> Pair a b -> Bool)
    -> (Pair a b -> Pair a b -> Bool)
    -> (Pair a b -> Pair a b -> Bool)
    -> (Pair a b -> Pair a b -> Bool)
    -> (Pair a b -> Pair a b -> Pair a b)
    -> (Pair a b -> Pair a b -> Pair a b)
    -> Ord (Pair a b)
    Pair a b -> Pair a b -> Bool
    Pair a b -> Pair a b -> Ordering
    Pair a b -> Pair a b -> Pair a b
    forall a.
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    Data)

    -- The definitions below are commented out because they are
    -- not used anywhere in the compiler, but are useful to showcase
    -- the intent behind this module (i.e. how it may evolve).
    --
    -- data Either a b = Left !a | Right !b
    --   deriving (Eq, Ord, Show, Functor, Foldable, Traversable, Data)
    --
    -- data List a = Nil | !a `Cons` !(List a)
    --   deriving (Eq, Ord, Show, Functor, Foldable, Traversable, Data)