Key.hs

-----------------------------------------------------------------------------
-- | Module     :  Data.Align.Key
--
-- 'These'-based zipping and unzipping of indexed functors.
--
-- @since 0.7.1
module Data.Align.Key (
    AlignWithKey (..),
    ) where

import Data.Key              (Key, Keyed (..))
import Data.Vector.Instances ()

import Data.Align
import Data.These

-- Instances
import Control.Applicative (ZipList)
import Data.Hashable       (Hashable)
import Data.HashMap.Strict (HashMap)
import Data.IntMap         (IntMap)
import Data.Map            (Map)
import Data.Sequence       (Seq)
import Data.Vector         (Vector)

-- | Keyed version of 'Align'.
--
-- @since 0.7.1
class (Keyed f, Align f) => AlignWithKey f where
    -- | Analogous to @'alignWith'@, but also provides an index.
    alignWithKey :: (Key f -> These a b -> c) -> f a -> f b -> f c
    alignWithKey f a b = mapWithKey f (align a b)

instance AlignWithKey Maybe
instance AlignWithKey []

-- | @since 0.7.6
instance AlignWithKey ZipList
instance AlignWithKey Seq
instance AlignWithKey IntMap
instance Ord k => AlignWithKey (Map k)
instance (Eq k, Hashable k) => AlignWithKey (HashMap k)
instance AlignWithKey Vector