It is a bit difficult to have static type checking, type inference, and dynamic code generation all working together seamlessly. If you have a macro expansion w

It is a bit difficult to have static type checking, type inference, and dynamic code generation all working together seamlessly. If you have a macro expansion whose types are entirely inferred, then naturally they should check properly, even if they are inferred improperly. The larger the macro, the more cryptic the errors are as well, since you could conceivably be generating entire functions whose output and input types are inferred based on very distant macro input and context, and such a type error is going to be very confusing to your users. C++ has this problem: simple errors can dump a dozen screens of template garbage on you.