Explore C++ pattern matching for open sum types in this CppNow 2019 conference talk by André Bergner. Dive into solutions for declarative dispatching and fast pattern matching over type hierarchies without relying on RTTI. Learn about the 'matchine' library implementation, which offers tools for modeling open sum types through inheritance. Discover techniques for sorting matching cases at compile time to enable binary search at runtime. Gain insights from a principal software engineer at Native Instruments on advanced C++ concepts, including std::variant, std::visit, and custom implementations for efficient pattern matching. Understand the challenges and potential of applying pattern matching as a library feature in C++, with practical examples and performance considerations.