It's an impressive project. One of the key problems for any safe language interoperating with C++ (even a safe C++ subset) is that you really want to be able to

It's an impressive project. One of the key problems for any safe language interoperating with C++ (even a safe C++ subset) is that you really want to be able to interact with C++ standard library types (string, vector etc) safely because they will appear at interface boundaries. Circle introduces its own safe standard library so I don't see how Circle fares here.