What happened to std::num::Primitive?

问题:

I found Primitive through Google but it appears to be from a pre-beta version and my compiler (beta 3) complains that it can't find it. Can anyone point me to where it has moved or if there is an equivalent? Web searching hasn't thrown up anything promising

回答1:

It was removed, since it wasn't being used at the time.

You can write your own marker trait of the form, though.