module Reflex.Updated
( UpdatedMap (..)
, Updated (..)
, split
, holdDyn', hold'
, holdMapDyn, holdMap
, shallowDiff
, shallowDiff'
) where
import Reflex
import Data.Monoid
import Data.Maybe
import Data.Functor
import Control.Lens
import Control.Monad.Fix
import Data.Map.Strict (Map)
import qualified Data.Map.Strict as Map
import Prelude
data UpdatedMap t k a = UpdatedMap (Map k a) (Event t (Map k (Maybe a)))
data Updated t a = Updated a (Event t a)
instance Reflex t => Functor (UpdatedMap t k) where
fmap f (UpdatedMap initial changes) = UpdatedMap (f <$> initial) (fmap (fmap f) <$> changes)
instance Reflex t => Functor (Updated t) where
fmap f (Updated initial changes) = Updated (f initial) (f <$> changes)
instance Reflex t => FunctorWithIndex k (UpdatedMap t k) where
imap f (UpdatedMap initial changes) = UpdatedMap (imap f initial) (imap (fmap . f) <$> changes)
split :: Functor f => f (a, b) -> (f a, f b)
split f = (fst <$> f, snd <$> f)
holdMapDyn :: (Reflex t, MonadHold t m, MonadFix m, Ord k) => UpdatedMap t k a -> m (Dynamic t (Map k a))
holdMapDyn (UpdatedMap initial changes) = foldDyn (flip (ifoldr modify)) initial changes
where
modify k Nothing items = Map.delete k items
modify k (Just item) items = Map.insert k item items
holdMap :: (Reflex t, MonadHold t m, MonadFix m, Ord k) => UpdatedMap t k a -> m (Behavior t (Map k a))
holdMap = (current <$>) . holdMapDyn
holdDyn' :: (Reflex t, MonadHold t m, MonadFix m) => Updated t a -> m (Dynamic t a)
holdDyn' (Updated initial changes) = holdDyn initial changes
hold' :: (Reflex t, MonadHold t m, MonadFix m) => Updated t a -> m (Behavior t a)
hold' (Updated initial changes) = hold initial changes
shallowDiff' :: (Ord k) => Map k a -> Map k b -> Map k (Maybe b)
shallowDiff' m m' = (Just <$> m' Map.\\ m) <> (const Nothing <$> m Map.\\ m')
shallowDiff :: (Reflex t, Ord k) => Behavior t (Map k a) -> Event t (Map k b) -> Event t (Map k (Maybe b))
shallowDiff currentItems updatedItems = ffilter (not . Map.null) $
attachWith shallowDiff' currentItems updatedItems