I'm probably not as up on the most modern c++ approaches as I should be but I'm quite interested. I have downloaded the code and I'm looking through it.

Basically, it uses template metaprogramming to go from the higher-level map/reduce/rise semantics to lower level for-loops and calls.

Beyond the particulars, the question/challenge I'd have would be - "how would you use this dynamically generate map/reduce/rise calls?"