Systems Need Languages Need Systems!

Domain-specific language and compiler extensions can significantly reduce the complexity of systems, especially when written in C or C++. However, instead of the current variety of ad-hoc implementation strategies, which include preprocessor macros, C++ templates, and custom-built language processors, system builders need a uniform and general facility for realizing their own extensions. In this paper, we argue that macros can provide this solution, as they provide a concise specification of how to transform a program at compile time. We develop the requirements for a suitable macro facility, outline the structure of the corresponding macro processor, called xtc for eXTensible C, and explore the implications of starting to build it. We conclude that only a tighter integration between system and language efforts can help us achieve the benefits of language and compiler extensibility and cope with the complexity of modern systems.