{-# LANGUAGE CPP #-}
{-# LANGUAGE MultiParamTypeClasses #-}
#ifdef USE_REFLEX_OPTIMIZER
{-# OPTIONS_GHC -fplugin=Reflex.Optimizer #-}
#endif
-- |
-- Module:
--   Reflex.Network
-- Description:
--   This module provides combinators for building FRP graphs/networks and modifying them dynamically.
module Reflex.Network
  ( networkView
  , networkHold
  , untilReady
  ) where

import Reflex.Class
import Reflex.Adjustable.Class
import Reflex.NotReady.Class
import Reflex.PostBuild.Class

-- | A 'Dynamic' "network": Takes a 'Dynamic' of network-creating actions and replaces the network whenever the 'Dynamic' updates.
-- The returned Event of network results fires at post-build time and when the 'Dynamic' updates.
-- Note:  Often, the type 'a' is an Event, in which case the return value is an Event-of-Events, where the outer 'Event' fires
-- when switching networks. Such an 'Event' would typically be flattened (via 'switchHoldPromptly').
networkView :: (NotReady t m, Adjustable t m, PostBuild t m) => Dynamic t (m a) -> m (Event t a)
networkView :: forall t (m :: * -> *) a.
(NotReady t m, Adjustable t m, PostBuild t m) =>
Dynamic t (m a) -> m (Event t a)
networkView Dynamic t (m a)
child = do
  postBuild <- m (Event t ())
forall t (m :: * -> *). PostBuild t m => m (Event t ())
getPostBuild
  let newChild = [Event t (m a)] -> Event t (m a)
forall {k} (t :: k) a. Reflex t => [Event t a] -> Event t a
leftmost [Dynamic t (m a) -> Event t (m a)
forall a. Dynamic t a -> Event t a
forall {k} (t :: k) a. Reflex t => Dynamic t a -> Event t a
updated Dynamic t (m a)
child, Behavior t (m a) -> Event t () -> Event t (m a)
forall {k} (t :: k) b a.
Reflex t =>
Behavior t b -> Event t a -> Event t b
tagCheap (Dynamic t (m a) -> Behavior t (m a)
forall a. Dynamic t a -> Behavior t a
forall {k} (t :: k) a. Reflex t => Dynamic t a -> Behavior t a
current Dynamic t (m a)
child) Event t ()
postBuild]
  snd <$> runWithReplace notReady newChild

-- | Given an initial "network" and an 'Event' of network-creating actions, create a network that is recreated whenever the Event fires.
-- The returned Dynamic of network results occurs when the Event does.
-- Note:  Often, the type 'a' is an Event, in which case the return value is a Dynamic-of-Events that would typically be flattened (via 'switchPromptlyDyn').
networkHold :: (Adjustable t m, MonadHold t m) => m a -> Event t (m a) -> m (Dynamic t a)
networkHold :: forall t (m :: * -> *) a.
(Adjustable t m, MonadHold t m) =>
m a -> Event t (m a) -> m (Dynamic t a)
networkHold m a
child0 Event t (m a)
newChild = do
  (result0, newResult) <- m a -> Event t (m a) -> m (a, Event t a)
forall a b. m a -> Event t (m b) -> m (a, Event t b)
forall t (m :: * -> *) a b.
Adjustable t m =>
m a -> Event t (m b) -> m (a, Event t b)
runWithReplace m a
child0 Event t (m a)
newChild
  holdDyn result0 newResult

-- | Render a placeholder network to be shown while another network is not yet
-- done building
untilReady :: (Adjustable t m, PostBuild t m) => m a -> m b -> m (a, Event t b)
untilReady :: forall t (m :: * -> *) a b.
(Adjustable t m, PostBuild t m) =>
m a -> m b -> m (a, Event t b)
untilReady m a
a m b
b = do
  postBuild <- m (Event t ())
forall t (m :: * -> *). PostBuild t m => m (Event t ())
getPostBuild
  runWithReplace a $ b <$ postBuild