Functional Programming with C++ Template Metaprograms

Template metaprogramming is an emerging new direction of generative programming: with the clever definitions of templates we can enforce the C++ compiler to execute algorithms at compilation time. Among the application areas of template metaprograms are the expression templates, static interface checking, code optimization with adaption, language embedding and active libraries. However, as this feature of C++ was not an original design goal, the language is not capable of elegant expression of template metaprograms. The complicated syntax leads to the creation of code that is hard to write, understand and maintain. Despite that template metaprogramming has a strong relationship with functional programming paradigm, language syntax and the existing libraries do not follow these requirements. In this paper we give a short and incomplete introduction to C++ templates and the basics of template metaprogramming. We will enlight the role of template metaprograms, some important and widely used idioms and techniques.