cpp/utility/functional/is bind expression

If is the type produced by a call to std (but not std or ), this template is derived from std. For any other type (unless user specialized), this template is derived from std.

This template may be specialized for a user-defined type to implement  with base characteristic of std to indicate that  should be treated by std as if it were the type of a bind subexpression: when a bind-generated function object is invoked, a bound argument of this type will be invoked as a function object and will be given all the unbound arguments passed to the bind-generated object.