F#是否了解其歧视工会的汇编表格? [英] Is F# aware of its discriminated unions' compiled forms?

问题描述

F#中的已区分联合被编译为抽象类，并且其选项变为嵌套的具体类.

A discriminated union in F# is compiled to an abstract class and its options become nested concrete classes.

type DU = A | B

DU是抽象的，而DU.A和DU.B是具体的.

DU is abstract while DU.A and DU.B are concrete.

使用ServiceStack，可以使用函数来自定义类型序列化为JSON字符串并返回.关于DU类型，这是我在C#中可以做到的方式.

With ServiceStack, the serialization of types to JSON strings and back can be customized with functions. With respect to the DU type, here's how I could do it in C#.

using ServiceStack.Text;

JsConfig<DU.A>.SerializeFn = v => "A"; // Func<DU.A, String>
JsConfig<DU.B>.SerializeFn = v => "B"; // Func<DU.B, String>
JsConfig<DU>.DeserializeFn = s =>
    if s == "A" then DU.NewA() else DU.NewB(); // Func<String, DU>

F#是否了解其歧视工会的汇编表格?在编译时如何获取F#中的DU.A类型?

Is F# aware of its discriminated unions' compiled forms? How would I get the type of DU.A in F# at compile time?

typeof<DU> // compiles
typeof<DU.A> // error FS0039: The type 'A' is not defined
typeof<A> // error FS0039: The type 'A' is not defined

我可以轻松地在F#中注册一个用于反序列化的函数.

I can easily enough register a function for deserialization in F#.

open System
open ServiceStack.Text

JsConfig<DU>.RawDeserializeFn <-
    Func<_, _>(fun s -> printfn "Hooked"; if s = "A" then A else B)

对于具体类型DU.A和DU.B，是否可以完全在F#中注册序列化功能?

Is it possible to register serialize functions wholly in F# for the concrete types DU.A and DU.B?

推荐答案

尽管所有行为(抽象类等)不仅是实现细节，而且实际上是由规范定义的，但这些东西在F#中是不可接受的-这是规范的报价

Whilst all the behaviour (the abstract classes etc.) is not just an implemenation detail, it is actually defined by the spec, these things are not accesible from F# - this is a quote from the spec

已编译的联合类型U具有:

A compiled union type U has:

·每个空联合案例都有一个CLI静态获取属性U.C C.此属性获取一个单例对象，该对象表示每个这样的对象 情况.

· One CLI static getter property U.C for each null union case C. This property gets a singleton object that represents each such case.

·每个非null联合案例C都有一个CLI嵌套类型U.C. 类型具有实例属性Item1，Item2.... 联合用例，或者只有一个实例属性Item(如果只有一个) 场地.但是，只有一种情况的已编译联合类型不会 具有嵌套类型.相反，联合类型本身扮演着 案例类型.

· One CLI nested type U.C for each non-null union case C. This type has instance properties Item1, Item2.... for each field of the union case, or a single instance property Item if there is only one field. However, a compiled union type that has only one case does not have a nested type. Instead, the union type itself plays the role of the case type.

·每个非空联合案例C的一个CLI静态方法U.NewC. 这种方法会为这种情况构造一个对象.

· One CLI static method U.NewC for each non-null union case C. This method constructs an object for that case.

·每个案例C都有一个CLI实例属性U.IsC. 属性会根据情况返回true或false.

· One CLI instance property U.IsC for each case C. This property returns true or false for the case.

·每个案例C的一个CLI实例属性U.Tag. 属性会获取或计算与大小写相对应的整数标签.

· One CLI instance property U.Tag for each case C. This property fetches or computes an integer tag corresponding to the case.

·如果U具有不止一种情况，则它具有一种CLI嵌套类型 U.Tags. U.Tags类型在每种情况下都包含一个整数文字，在 从零开始递增顺序.

· If U has more than one case, it has one CLI nested type U.Tags. The U.Tags typecontains one integer literal for each case, in increasing order starting from zero.

·编译的联合类型具有所需的方法 实施其自动生成的接口，以及任何其他功能 用户定义的属性或方法.

· A compiled union type has the methods that are required to implement its auto-generated interfaces, in addition to any user-defined properties or methods.

这些方法和属性可能无法直接在F#中使用. 但是，这些类型具有面向用户的List.Empty，List.Cons， Option.None和Option.Some一些属性和/或方法.

These methods and properties may not be used directly from F#. However, these types have user-facing List.Empty, List.Cons, Option.None, and Option.Some properties and/or methods.

重要的是，"F#可能无法使用这些方法和属性".

Importantly, "these methods and properties may not be used from F#".

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