Advances in energy harvesting circuits and energy efficient architecture of processors create the potential for batteryless computing and sensing systems called transiently powered computers. These computers can only operate intermittently due to fluctuating nature of ambient energy. Intermittent operation requires a new programming model that should preserve forward progress and maintain data consistency; which are challenging. We propose a structured task-based programming model; namely PureMEM, to cope with these challenges. We discuss how PureMEM prevents interdependencies caused by the unstructured control encountered in intermittent operation, enables re-usability of the tasks, provides dynamic memory management and supports error handling. We also present intermittent programs to exemplify the features of PureMEM.