Also there's work towards a pure C++ abstraction layer for programming these accelerators, called SYCL [0]. It lets you define your compute kernels using normal C++ lambdas or functions, and then automatically infers the data dependencies to do the kernel execution. In particular, it provides an implementation of the C++ "Parallel STL" [1] (some intro slides at [2]), which in turn provides "execution policies" for various standard library functions, such as sorting. The aim is precisely the kind of thing you're talking about!

[0] I found a nice intro at https://blog.tartanllama.xyz/sycl/

[1] http://en.cppreference.com/w/cpp/experimental/parallelism

[2] https://www.khronos.org/assets/uploads/developers/library/20...