I agree with you in spirit, but yours was a poor example given the known issues with rand() and the fact that the C++ version is not at all difficult to use and

I agree with you in spirit, but yours was a poor example given the known issues with rand() and the fact that the C++ version is not at all difficult to use and accounts for rand()'s warts. Besides, writing a standard library is a great example of when you _do_ need to account for pretty much every use case and write sufficiently generic API's.