Question

我正在尝试编写自定义DivideByInt，如下所示

type Pair = Pair of int * int with
    static member DivideByInt pair int = pair


[<EntryPoint>]
let main argv =
    LanguagePrimitives.DivideByInt (Pair(1,2)) 1 
    |> ignore 
    0

// compiler error: "FS0001: Method or object constructor 'DivideByInt' not found"

为什么编译器找不到Pair.DivideByInt？

Answer 1

Pair.DivideByInt必须将元组作为输入

更正后的版本：

type Pair = Pair of int * int with
    static member DivideByInt (pair, int) = pair

Answer 2

类型int不是一个好的起点，因为它不支持DivideByInt，但你可以使类型通用：

type Pair<'t> = Pair of 't * 't with
    static member inline DivideByInt (Pair (x, y), i:int) =
        Pair (LanguagePrimitives.DivideByInt x i, LanguagePrimitives.DivideByInt y i)


[<EntryPoint>]
let main argv =
    LanguagePrimitives.DivideByInt (Pair (1.0, 2.0)) 1 |> ignore 
    LanguagePrimitives.DivideByInt (Pair (1m , 2m )) 1 |> ignore 
    0

否则你可以“强制”它在一对int上工作并保持通用：

type Pair<'t> = Pair of 't * 't with
    static member inline DivideByInt (Pair (x, y), i:int) =
        Pair (LanguagePrimitives.DivideByInt x i, LanguagePrimitives.DivideByInt y i)
    static member DivideByInt (Pair (x:int, y:int), i:int) =
        Pair (x / i, y / i)
    static member DivideByInt (Pair (x:uint32, y:uint32), i:int) =
        Pair (x / uint32 i, y / uint32 i)

Answer 3

这对我有用：

LanguagePrimitives.DivideByInt 3.0 4
|> printfn "%A"

所以它没有得到元组，但有两个论点。以上给出结果：0.75

如何实现DivideByInt

3 个答案: