It is also useful for rewriting routines in the critical path for slower, but more productive languages. Particularly languages that need to do a lot of heavy-d

It is also useful for rewriting routines in the critical path for slower, but more productive languages. Particularly languages that need to do a lot of heavy-duty data crunching (think Python, R, Matlab, Octave). I mean, I guess you could do that in C++ instead. But why would you bother if C is good enough (and it typically is for most numerical algorithms).