具有特定类型和属性的枚举

Question

我想验证动物是否为人，其名称为Alex。

人物对象：

type Person(name: string) =
        member this.Name = name

Enumration：

type Animal =
| Person of Person
| Cat
| Dog

模式匹配：

let KnowAnimal animal =
    match animal with
    | Person person && person.Name = "Alex" -> 1
    | Cat -> 2
    | Dog -> 3
    | _ -> 4

Answer 1

您可以使用when指定图案防护：

let KnowAnimal animal =
    match animal with
    | Person person when person.Name = "Alex" -> 1
    | Cat -> 2
    | Dog -> 3
    | _ -> 4