波蘇斯

一些最簡單的類是 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，引入了類似於 C#auto-properties 的自動屬性，

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

建立任一個例項都是類似的，

// 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變值，則記錄型別更加慣用 F#。

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

並且可以建立此記錄：

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

也可以通過指定現有記錄並新增 with，然後新增要覆蓋的欄位列表，根據其他記錄建立記錄：

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