Ring Bell in Haskell (no jummed, not override monad operators)

RingBell.hs

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE GADTs #-}
{-# language RankNTypes #-}


data DoorState = DoorClosed | DoorOpen
    deriving Show

data DoorCmd before end a where
    Open  :: DoorCmd DoorClosed DoorOpen ()
    Close :: DoorCmd DoorOpen DoorClosed ()
    Ring  :: DoorCmd DoorClosed DoorClosed ()

    Pure  :: a -> DoorCmd s1 s2 a
    Bind  :: DoorCmd s1 s2 a -> (forall a. a -> DoorCmd s2 s3 b) -> DoorCmd s1 s3 b

run :: DoorCmd before after a -> IO DoorState
run Ring = do 
    putStrLn "Ring Ring"
    return DoorClosed
run Open = do 
    putStrLn "Open"
    return DoorOpen
run Close = do
    putStrLn "Close"
    return DoorClosed
run (Bind cmd nextFn) = do
    nextState <- run cmd
    run (nextFn nextState)

doorProg :: DoorCmd DoorClosed DoorClosed ()
doorProg = Bind (Bind Ring (\_ -> Open)) (\_ -> Close)

main :: IO ()
main = do
    run doorProg
    putStrLn "Finished"