You can achieve this level of control using monad transformers or extensible effects -- this is a standard technique in Haskell. frignate :: (MonadDB m) =>

You can achieve this level of control using monad transformers or extensible effects -- this is a standard technique in Haskell. frignate :: (MonadDB m) => Config -> m Int frignate cfg = do db <- getDB ... return 1 And it is composable, so if a function calls a function that uses one of the managed resources then the requirement propagates upward. And you can swap in non-IO based instances for testing, or whatever else you want.