It's worth noting that Regent is the language that implements the Legion programming model. The Legion runtime system is just a C++ library with bindings for C,

It's worth noting that Regent is the language that implements the Legion programming model. The Legion runtime system is just a C++ library with bindings for C, Fortran, Python, Terra, and Lua. Writing Regent code is much higher productivity than writing to the C++ Legion library directly, but if you want to you can drop down and write your tasks in any of the other languages that Legion supports. You can even mix and match tasks written in different languages.