Good read, thanks. But in practice, with all its problems, C++ has been proven to work over and over, and the author's - Tim Sweeney - work is proof of that. Today, 6 years after this talk, has anyone successfully made a commercial game with the game logic built with FP, and if so, was it more productive than the former approach? I'm not saying the lack of examples prove it's not beneficial, but believing it is, is still only a guess.