{-#LANGUAGE LambdaCase,TemplateHaskell,KindSignatures,DataKinds,TypeFamilies#-}
import Effectful
import Effectful.Dispatch.Dynamic
import Data.Kind(Type)
import Effectful.State.Static.Shared

data Event e m a where
  RegisterHandler :: (e -> m ()) -> Event e m ()
  RaiseEvent :: e -> Event e m ()

registerHandler ::Event e :> es => (e -> Eff es ()) -> Eff es ()
registerHandler = send . RegisterHandler
raiseEvent :: Event e :> es => e -> Eff es ()
raiseEvent = send . RaiseEvent
type instance DispatchOf (Event e) = 'Dynamic
runEvent ::forall e es a. Eff (Event e ': es) a -> Eff es a
runEvent = reinterpret (evalState ([]::[e -> Eff es ()])) $ \env -> \case
  (RegisterHandler act) -> localUnlift env (ConcUnlift Persistent Unlimited) $ \unlift  -> modify @([e -> Eff es ()]) ((unlift . act) :)