module Data.Bifoldable
( Bifoldable(..)
, bifoldr'
, bifoldrM
, bifoldl'
, bifoldlM
, bitraverse_
, bifor_
, bimapM_
, biforM_
, bisequenceA_
, bisequence_
, biList
, biconcat
, biconcatMap
, biany
, biall
) where
import Control.Applicative
import Data.Monoid
class Bifoldable p where
bifold :: Monoid m => p m m -> m
bifold = bifoldMap id id
bifoldMap :: Monoid m => (a -> m) -> (b -> m) -> p a b -> m
bifoldMap f g = bifoldr (mappend . f) (mappend . g) mempty
bifoldr :: (a -> c -> c) -> (b -> c -> c) -> c -> p a b -> c
bifoldr f g z t = appEndo (bifoldMap (Endo . f) (Endo . g) t) z
bifoldl :: (c -> a -> c) -> (c -> b -> c) -> c -> p a b -> c
bifoldl f g z t = appEndo (getDual (bifoldMap (Dual . Endo . flip f) (Dual . Endo . flip g) t)) z
instance Bifoldable (,) where
bifoldMap f g (a, b) = f a `mappend` g b
instance Bifoldable Either where
bifoldMap f _ (Left a) = f a
bifoldMap _ g (Right b) = g b
bifoldr' :: Bifoldable t => (a -> c -> c) -> (b -> c -> c) -> c -> t a b -> c
bifoldr' f g z0 xs = bifoldl f' g' id xs z0 where
f' k x z = k $! f x z
g' k x z = k $! g x z
bifoldrM :: (Bifoldable t, Monad m) => (a -> c -> m c) -> (b -> c -> m c) -> c -> t a b -> m c
bifoldrM f g z0 xs = bifoldl f' g' return xs z0 where
f' k x z = f x z >>= k
g' k x z = g x z >>= k
bifoldl':: Bifoldable t => (a -> b -> a) -> (a -> c -> a) -> a -> t b c -> a
bifoldl' f g z0 xs = bifoldr f' g' id xs z0 where
f' x k z = k $! f z x
g' x k z = k $! g z x
bifoldlM :: (Bifoldable t, Monad m) => (a -> b -> m a) -> (a -> c -> m a) -> a -> t b c -> m a
bifoldlM f g z0 xs = bifoldr f' g' return xs z0 where
f' x k z = f z x >>= k
g' x k z = g z x >>= k
bitraverse_ :: (Bifoldable t, Applicative f) => (a -> f c) -> (b -> f d) -> t a b -> f ()
bitraverse_ f g = bifoldr ((*>) . f) ((*>) . g) (pure ())
bifor_ :: (Bifoldable t, Applicative f) => t a b -> (a -> f c) -> (b -> f d) -> f ()
bifor_ t f g = bitraverse_ f g t
bimapM_:: (Bifoldable t, Monad m) => (a -> m c) -> (b -> m d) -> t a b -> m ()
bimapM_ f g = bifoldr ((>>) . f) ((>>) . g) (return ())
biforM_ :: (Bifoldable t, Monad m) => t a b -> (a -> m c) -> (b -> m d) -> m ()
biforM_ t f g = bimapM_ f g t
bisequenceA_ :: (Bifoldable t, Applicative f) => t (f a) (f b) -> f ()
bisequenceA_ = bifoldr (*>) (*>) (pure ())
bisequence_ :: (Bifoldable t, Monad m) => t (m a) (m b) -> m ()
bisequence_ = bifoldr (>>) (>>) (return ())
biList :: Bifoldable t => t a a -> [a]
biList = bifoldr (:) (:) []
biconcat :: Bifoldable t => t [a] [a] -> [a]
biconcat = bifold
biconcatMap :: Bifoldable t => (a -> [c]) -> (b -> [c]) -> t a b -> [c]
biconcatMap = bifoldMap
biany :: Bifoldable t => (a -> Bool) -> (b -> Bool) -> t a b -> Bool
biany p q = getAny . bifoldMap (Any . p) (Any . q)
biall :: Bifoldable t => (a -> Bool) -> (b -> Bool) -> t a b -> Bool
biall p q = getAll . bifoldMap (All . p) (All . q)