Sure, that's why I called it a language design issue. Library users want generic and convenient interfaces (which arguably, boost does very well), there is ju

Sure, that's why I called it a language design issue. Library users want generic and convenient interfaces (which arguably, boost does very well), there is just no way with modern C++ to keep the nice interfaces and at the same time put a significant amount of logic in a source file. It is not surprising that boost choose convenience over tradition and fast compile speeds.