波苏斯

一些最简单的类是 POCO。

// C#
public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public DateTime Birthday { get; set; }
}

在 F#3.0 中，引入了类似于 C#auto-properties 的自动属性，

// F#
type Person() = 
    member val FirstName = "" with get, set
    member val LastName = "" with get, set
    member val BirthDay = System.DateTime.Today with get, set

创建任一个实例都是类似的，

// C#
var person = new Person { FirstName = "Bob", LastName = "Smith", Birthday = DateTime.Today }; 
// F#
let person = new Person(FirstName = "Bob", LastName = "Smith")

如果你可以使用不可变值，则记录类型更加惯用 F#。

type Person = { 
    FirstName:string; 
    LastName:string; 
    Birthday:System.DateTime 
} 

并且可以创建此记录：

let person = { FirstName = "Bob"; LastName = "Smith"; Birthday = System.DateTime.Today }

也可以通过指定现有记录并添加 with，然后添加要覆盖的字段列表，根据其他记录创建记录：

let formal = { person with FirstName = "Robert" }