{-# LANGUAGE RankNTypes #-}
module Main where

import Reactive.Banana
import Reactive.Banana.Frameworks
import Reactive.Banana.Switch
import Data.IORef
import Control.Monad

main = do
    fShowRef <- newIORef (const (return ()))
    fNumRef <- newIORef (const (return ()))
    let
        netDesc :: forall t. Frameworks t => Moment t ()
        netDesc = do
            (eNum, fNum) <- newEvent
            (eShow, fShow) <- newEvent
            liftIO (writeIORef fShowRef fShow)
            liftIO (writeIORef fNumRef fNum)
            let beh = stepper 0 eNum
            behTrimmed <- trimB beh
            reactimate (printInitial behTrimmed <$ eShow)

    actuate =<< compile netDesc

    fNum <- readIORef fNumRef
    fNum 1
    fShow <- readIORef fShowRef
    fShow ()

printInitial :: AnyMoment Behavior Int -> IO ()
printInitial beh = do
    let
        netDesc :: forall t. Frameworks t => Moment t ()
        netDesc = do
            behNow <- now beh
            initVal <- initial behNow
            liftIO (print initVal)
    -- compiling is enough, I just want to see the initial value
    void (compile netDesc)

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