-- | An empty map of handlers.
emptyHandlerMap :: HandlerMap a
emptyHandlerMap  = HandlerMap
  { handlers      = Map.empty
  , handlerNextId = 0
  }
emptyHandlerMap :: HandlerMap a
emptyHandlerMap  = HandlerMap
  { handlers      = Map.empty
  , handlerNextId = 0
  }
emptyHandlerMap  = HandlerMap
  { handlers      = Map.empty
  , handlerNextId = 0
  }