如何使用F＃將結構體的值設置爲'Item`＃

Question

如何將value設置爲Item struct？我嘗試了以下兩種類型，但都以value must be mutable錯誤結束。

module Test1 = 
    [<Struct>] 
    type Test (array: float []) = 
    member o.Item 
     with get i = array.[i] 
     and set i value = array.[i] <- value 

    let test = Test [|0.0|] 
    test.[0] <- 4.0 

module Test2 = 

    [<Struct>] 
    type Test = 
    val mutable array: float [] 
    new (array: float []) = { array = array } 
    member o.Item 
     with get i = o.array.[i] 
     and set i value = o.array.[i] <- value 

    let test = Test [|0.0|] 
    test.[0] <- 4.0 

Answer 1

請嘗試更換：

let test = Test [|0.0|] 

有：

let mutable test = Test [|0.0|]