The kind traits
Rust types can be classified in various useful ways according to intrinsic properties of the type. These classifications, often called 'kinds', are represented as traits.
They cannot be implemented by user code, but are instead implemented by the compiler automatically for the types to which they apply.
Freeze - Types that are either immutable or have inherited mutability.Send - Types able to be transferred across task boundaries.Sized - Types with a constant size known at compile-time.FreezeTypes that are either immutable or have inherited mutability.
SendTypes able to be transferred across task boundaries.
SizedTypes with a constant size known at compile-time.