{-# LANGUAGE RecursiveDo #-}
import Control.Applicative
import Control.Monad
import Data.Maybe

import qualified Graphics.UI.Threepenny as UI
import Graphics.UI.Threepenny.Core

main :: IO ()
main = startGUI defaultConfig setup

setup :: Window -> UI ()
setup w = mdo
    return w # set UI.title "Simple example"

    display     <- UI.textarea  # set UI.text "Initial value"
    listBox     <- UI.listBox   (pure ["first", "second"]) listB ((UI.string .) <$> (pure id))
    listB       <- stepper Nothing (rumors $ UI.userSelection listBox)
    button      <- UI.button    # set UI.text "Button"
    cutedListB  <- stepper Nothing (listB <@ UI.click button)

    element listBox # set (attr "size") "10"

    getBody w   #+ [element listBox, element button, element display]

    on UI.click button $ const $ do
        element display # sink UI.text ((maybe "new text" id) <$> cutedListB)