Haskell 2010
4. Declarations and Bindings
4.1 Overview of Types and Classes
4.1.2 Syntax of Types
- Type variables
- Type constructors
- type constants with kind ∗
- types with kind ∗ → ∗
- built-in type constructors
- trivial type, as () with *
- function type, as (->), kind ∗ → ∗ → ∗
- list type, as [], kind ∗ → ∗
- tuple types, as (,), (,,), and so on, kind ∗ → ∗ → ∗ and so on.
- Special syntax, built-in type constructors for functions, tuples, and lists,
- function type, t1 -> t2
- tuple type, (t1, . . . , tk)
- list type, [t]
- Type application, 接收类型化参数，具化为新类型
- A parenthesized type, form (t), is identical to the type t.
4.2 User-Defined Datatypes
- algebraic datatypes (data declarations)
- renamed datatypes (newtype declarations)
- type synonyms (type declarations)
4.2.1 Algebraic Datatype Declarations
示例：
-- libraries/ghc-prim/GHC/Types.hs
data List a = [] | a : List a