import Haste

main :: IO ()
main = do
    Just inp  <- elemById "user-input"
    Just outp <- elemById "script-output"
    onEvent inp OnKeyUp $ \_ -> do
        text <- getProp inp "value"
        setProp outp "innerHTML" text
    return ()

-- Alternative that uses `withElems` to retrieve the elements from the document
main_alt :: IO ()
main_alt = withElems ["user-input","script-output"] script
  where
    script [inp,outp] = do
        onEvent inp OnKeyUp $ \_ -> do
            text <- getProp inp "value"
            setProp outp "innerHTML" text
        return ()