a kind is the type of a  or, less commonly, the type of a .

 

• , pronounced "type", is the kind of all  seen as  type constructors, and also called proper types in this context. This normally includes function types in .
•  is the kind of a  , e.g. of a  constructor.
•  is the kind of a  type constructor (via ), e.g. of a  constructor, and also that of a  constructor (not to be confused with the result of its application, which itself is a function type, thus of kind )
•  is the kind of a higher-order type operator from unary type constructors to proper types.

https://www.cnblogs.com/feng9exe/p/9155649.html

https://en.wikipedia.org/wiki/Kind_(type_theory)

 

type多指具体的

kind多指抽象的

kind - 种类

type - 类型