Learning Functional Programming in Go

Kinds of types

Functors in Haskell must have the kind * -> *. Kinds are another layer of types, above the concrete types in Haskell. Kinds allow us to define what behavior types are capable of and then connect them with the appropriate type classes. For example, an Int can act like a showable, readable, ordered, or enumerable thing. Values in Haskell can be classified by their type. Let's use Haskell's concise syntax to look at some examples:

Type(Class)	__Kind__	Description
Int	*	* represents concrete types (such as Bool, Char, or Int).
Char	*	* represents concrete types (such as Bool, Char, or Int).
[]	* -> *	[] takes a single type of kind * and returns a new type of kind *.
Maybe	* -> *	A higher-kinded ...