ref: c101325aaf8ed0ec3c8c4ff4b7d425bba799825a
dir: /lib/Data/Bitraversable.hs/
{-# LANGUAGE Trustworthy #-}
{-# LANGUAGE ScopedTypeVariables #-}
-----------------------------------------------------------------------------
-- |
-- Module : Data.Bitraversable
-- Copyright : (C) 2011-2016 Edward Kmett
-- License : BSD-style (see the file LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : provisional
-- Portability : portable
--
-- @since 4.10.0.0
----------------------------------------------------------------------------
module Data.Bitraversable
( Bitraversable(..)
, bisequenceA
, bisequence
, bimapM
, bifor
, biforM
, bimapAccumL
, bimapAccumR
-- , bimapDefault
-- , bifoldMapDefault
) where
import Control.Applicative
import Data.Bifunctor
import Data.Bifoldable
-- Data.Coerce
import Data.Functor.Identity(Identity(..))
import Data.Foldable.Internal(StateL(..), runStateL, StateR(..), runStateR)
class (Bifunctor t, Bifoldable t) => Bitraversable t where
bitraverse :: Applicative f => (a -> f c) -> (b -> f d) -> t a b -> f (t c d)
bisequenceA :: (Bitraversable t, Applicative f) => t (f a) (f b) -> f (t a b)
bisequenceA = bisequence
bimapM :: (Bitraversable t, Applicative f)
=> (a -> f c) -> (b -> f d) -> t a b -> f (t c d)
bimapM = bitraverse
bisequence :: (Bitraversable t, Applicative f) => t (f a) (f b) -> f (t a b)
bisequence = bitraverse id id
{-
instance Bitraversable (,) where
bitraverse f g ~(a, b) = liftA2 (,) (f a) (g b)
instance Bitraversable ((,,) x) where
bitraverse f g ~(x, a, b) = liftA2 ((,,) x) (f a) (g b)
instance Bitraversable ((,,,) x y) where
bitraverse f g ~(x, y, a, b) = liftA2 ((,,,) x y) (f a) (g b)
instance Bitraversable ((,,,,) x y z) where
bitraverse f g ~(x, y, z, a, b) = liftA2 ((,,,,) x y z) (f a) (g b)
instance Bitraversable ((,,,,,) x y z w) where
bitraverse f g ~(x, y, z, w, a, b) = liftA2 ((,,,,,) x y z w) (f a) (g b)
instance Bitraversable ((,,,,,,) x y z w v) where
bitraverse f g ~(x, y, z, w, v, a, b) =
liftA2 ((,,,,,,) x y z w v) (f a) (g b)
-}
instance Bitraversable Either where
bitraverse f _ (Left a) = Left <$> f a
bitraverse _ g (Right b) = Right <$> g b
instance Bitraversable Const where
bitraverse f _ (Const a) = Const <$> f a
bifor :: (Bitraversable t, Applicative f)
=> t a b -> (a -> f c) -> (b -> f d) -> f (t c d)
bifor t f g = bitraverse f g t
biforM :: (Bitraversable t, Applicative f)
=> t a b -> (a -> f c) -> (b -> f d) -> f (t c d)
biforM = bifor
bimapAccumL :: Bitraversable t => (a -> b -> (a, c)) -> (a -> d -> (a, e))
-> a -> t b d -> (a, t c e)
bimapAccumL f g s t
= runStateL (bitraverse (StateL . flip f) (StateL . flip g) t) s
bimapAccumR :: Bitraversable t => (a -> b -> (a, c)) -> (a -> d -> (a, e))
-> a -> t b d -> (a, t c e)
bimapAccumR f g s t
= runStateR (bitraverse (StateR . flip f) (StateR . flip g) t) s
{-
bimapDefault = coerce
(bitraverse :: (a -> Identity b)
-> (c -> Identity d) -> t a c -> Identity (t b d))
bifoldMapDefault :: forall t m a b . (Bitraversable t, Monoid m)
=> (a -> m) -> (b -> m) -> t a b -> m
bifoldMapDefault = coerce
(bitraverse :: (a -> Const m ())
-> (b -> Const m ()) -> t a b -> Const m (t () ()))
-}