I expect that the middle ground of C+HLL is more common than the purist approach simply because it makes sense to use the right tools for very different jobs.

I expect that the middle ground of C+HLL is more common than the purist approach simply because it makes sense to use the right tools for very different jobs. I know that Eve is Python on top of a large, custom C++ code base. Civ and Blender as well. Adobe's Lightroom is a nice case study of 50% C++ and 50% Lua. I've never used Python+Weave, but it makes total sense. I do think Python's built-in CTypes library is unfortunately underused. (highlights: You can create C-callable function pointers and you can call C DLL functions from default Python. No add-on libs required.)