F#中Item属性的类型

Question

考虑界面:

type IVector = 
    abstract Item : int -> float

现在,让我们定义类:

type DenseVector(size : int) = 
    let mutable data = Array.zeroCreate size

    interface IVector with 
        member this.Item with get n = data.[n]

如何提供一种方法来改变密集向量的第n个条目？然后,将上面的代码修改为:

type DenseVector(size : int) = 
    let mutable data = Array.zeroCreate size

    interface IVector with 
        member this.Item with get n = data.[n]
                          and set n value = data.[n] <- value

不过,我得到,因为抽象方法的签名下面的错误Item的IVector界面:

未找到与此覆盖对应的抽象属性.

那么,究竟应该是签名Item的IVector？

Answer 1

type IVector =  
    abstract Item : int -> float with get, set