使用单位作为类型参数和覆盖方法 [英] Using unit as Type Parameter and overriding methods

问题描述

我基本上是在问为什么以下几行代码不能编译:

I'm basically asking why the following lines of codes do not compile:

type IGenericType<'a> = 
    abstract member MyFunc : 'a -> 'a -> 'a

type Implementer() = 
    member x.Test () () = () // unit->unit->unit
    interface IGenericType<unit> with 
        member x.MyFunc a b = b // FS0017
        // member x.MyFunc () () = () // FS0017

只是想知道是否有一种方法可以使此工作按预期进行.我认为这是单元和泛型实现所必需的限制.

Just curious if there is a method to make this work as intended. I assume this is a limitation which has to to with the implementation of unit and generics.

我目前正在使用以下解决方法:

Im using the following workaround at the moment:

type Nothing = 
    | Nothing
type Implementer() = 
    interface IGenericType<Nothing> with 
        member x.MyFunc a b = b

希望有人可以对此行为有所了解.

Hope someone can bring some light over this behavior.

推荐答案

您猜对了.为了在.NET Framework中实现互操作性，F#编译器不会为unit发出IL，而是将其替换为void.

You guessed it right. For interoperability inside .NET framework, F# compiler doesn't emit IL for unit but replace it by void instead.

因此，您的通用接口可用于除unit之外的任何类型.这似乎不是什么大问题；您的解决方法是解决此问题的不错方法.

Therefore, your generic interface works on any type but unit. It doesn't seem to be a big problem; your workaround is a nice solution for this issue.

更详细的讨论可以在由于单元导致的F#接口继承失败中找到.

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