Instantiated 'Dao.Struct.Update' into the 'Dao.Predicate.ErrorMonadPlus' and 'Control.Monad.Error' monad transformers, which allows me to use 'Dao.Predicate.mapPFail' in the 'Dao.Struct.atAddress' monad to prepend the address passed to 'Dao.Struct.atAddress' to a fail value, which means now error reporting in the 'Dao.Struct.Update' monad will tell the exact address of the failure.