The last section, "Checked bending of the rules" seems pretty similar to C++ contracts[0], though the behavior on violations looks like it will be able to vary

The last section, "Checked bending of the rules" seems pretty similar to C++ contracts[0], though the behavior on violations looks like it will be able to vary wildly between consteval and regular contexts, and whether it terminates the running program with a contract violation handler. [0] https://en.cppreference.com/w/cpp/language/contracts https://en.cppreference.com/w/cpp/language/contracts