    {-# LANGUAGE NamedFieldPuns #-}
    {-# LANGUAGE RecursiveDo #-}
    {-# LANGUAGE ScopedTypeVariables #-}
    {-----------------------------------------------------------------------------
        reactive-banana
    ------------------------------------------------------------------------------}
    module Reactive.Banana.Prim.Mid.IO where

    import Control.Monad.IO.Class
        ( liftIO )
    import qualified Data.Vault.Lazy        as Lazy

    import Reactive.Banana.Prim.Mid.Combinators (mapP)
    import Reactive.Banana.Prim.Mid.Evaluation  (step)
    import Reactive.Banana.Prim.Mid.Plumbing
    import Reactive.Banana.Prim.Mid.Types
    import qualified Reactive.Banana.Prim.Low.Ref as Ref

    debug :: String -> a -> a
    debug :: forall a. String -> a -> a
    debug String
    _ = a -> a
    forall a. a -> a
    id

    {-----------------------------------------------------------------------------
        Primitives connecting to the outside world
    ------------------------------------------------------------------------------}
    -- | Create a new pulse in the network and a function to trigger it.
    --
    -- Together with 'addHandler', this function can be used to operate with
    -- pulses as with standard callback-based events.
    newInput :: forall a. Build (Pulse a, a -> Step)
    newInput :: forall a. Build (Pulse a, a -> Step)
    newInput = mdo
        always <- Build (Pulse ())
    alwaysP
        _key   <- liftIO Lazy.newKey
        nodeP  <- liftIO $ Ref.new $ P $ PulseD
            { _keyP      = _key
            , _seenP     = agesAgo
            , _evalP     = readPulseP pulse    -- get its own value
            , _nameP     = "newInput"
            }
        let pulse = Pulse{Key (Maybe a)
    _key :: Key (Maybe a)
    _key :: Key (Maybe a)
    _key,_nodeP :: Ref SomeNodeD
    _nodeP=Ref SomeNodeD
    nodeP}
        -- Also add the  alwaysP  pulse to the inputs.
        let run :: a -> Step
            run a
    a = Inputs -> Step
    step ([Ref SomeNodeD
    nodeP, Pulse () -> Ref SomeNodeD
    forall a. Pulse a -> Ref SomeNodeD
    _nodeP Pulse ()
    always], Key (Maybe a) -> Maybe a -> Vault -> Vault
    forall a. Key a -> a -> Vault -> Vault
    Lazy.insert Key (Maybe a)
    _key (a -> Maybe a
    forall a. a -> Maybe a
    Just a
    a) Vault
    Lazy.empty)
        pure (pulse, run)

    -- | Register a handler to be executed whenever a pulse occurs.
    --
    -- The pulse may refer to future latch values.
    addHandler :: Pulse (Future a) -> (a -> IO ()) -> Build ()
    addHandler :: forall a. Pulse (Future a) -> (a -> IO ()) -> Build ()
    addHandler Pulse (Future a)
    p1 a -> IO ()
    f = do
        p2 <- (Future a -> IO (IO ()))
    -> Pulse (Future a) -> Build (Pulse (IO (IO ())))
    forall a b. (a -> b) -> Pulse a -> Build (Pulse b)
    mapP ((a -> IO ()) -> Future a -> IO (IO ())
    forall a b. (a -> b) -> IO a -> IO b
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap a -> IO ()
    f) Pulse (Future a)
    p1
        addOutput p2

    -- | Read the value of a 'Latch' at a particular moment in time.
    readLatch :: Latch a -> Build a
    readLatch :: forall a. Latch a -> Build a
    readLatch = Latch a -> Build a
    forall a. Latch a -> Build a
    readLatchB