Metaprogramming in functional C++

Metaprogramming can be treated as another programming paradigm. It's a totally different approach to coding because we are not dealing with the regular process of programming. By a regular process, we mean the three phases that a program goes through in its lifetime: coding, compiling, and running. It's obvious that a program does what it's supposed to do when it is executed. An executable is generated by the compiler through compilation and linking. Metaprogramming, on the other hand, is where the code is being executed during the compilation of the code. This might sound magical if you are dealing with it for the first time. How can we execute code if the program doesn't even exist yet? Recalling what we learned about templates in Chapter 4, Understanding and Designing Templates, we know that the compiler processes them with...