Pure nested-parallelism programming models are appealing due to their ease of programming and good analysis and debugging properties. Although their simple synchronization structure is appropriate to represent abstract parallel algorithms, it does not take into account many implementation issues. In this work we present key features of the evolution of a programming system based on high-level, nestedparallel specifications. They allow to easily express complex combinations of data and task

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... lelism with a common scheme, and to hide the layout and scheduling details. The approach allows the development of a modular compiler where automatic transformation techniques may exploit lower level and more complex synchronization structures, unlocking the limitations of pure nested-parallel programming.