F#中的静态解析字符串转换函数 [英] Statically resolved string conversion function in F#

问题描述

我正在尝试在F#中创建一个函数，该函数会将某些类型转换为字符串，但不能将其他类型转换为字符串.目的是使得可以传递基元，而不会偶然传递复杂的对象.这是我到目前为止的内容:

I'm trying to create a function in F# that will convert certain types to a string, but not others. The objective is so that a primitive can be passed but a complex object cannot be passed by accident. Here's what I have so far:

type Conversions =
    static member Convert (value:int) =
        value.ToString()
    static member Convert (value:bool) =
        value.ToString()

let inline convHelper< ^t, ^v when ^t : (static member Convert : ^v -> string) > (value:^v) =
    ( ^t : (static member Convert : ^v -> string) (value))

let inline conv (value:^v) = convHelper<Conversions, ^v>(value)

不幸的是，我的conv函数收到以下编译时错误:

Unfortunately, my conv function gets the following compile-time error:

A unique overload for method 'Convert' could not be determined based on type information
prior to this program point. A type annotation may be needed. Candidates: 
    static member Conversions.Convert : value:bool -> string, 
    static member Conversions.Convert : value:int -> string

我在做什么错了?

推荐答案

这似乎可行:

type Conversions = Conversions with 
    static member ($) (Conversions, value: int) = value.ToString()
    static member ($) (Conversions, value: bool) = value.ToString()

let inline conv value = Conversions $ value

conv 1 |> ignore
conv true |> ignore
conv "foo" |> ignore //won't compile

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