声明中的C#/F#差异很奇怪，代码在C#中编译，但在F#中没有 [英] Weird C# / F# difference in a declaration, code compiling in C# but not in F#

问题描述

该行是为InfluxDB驱动程序实例化数据点队列:

The line is to instantiate a queue of data points for the InfluxDB driver:

C#

Events = new ConcurrentQueue<InfluxDatapoint<InfluxValueField>>();

F#

let Events = new ConcurrentQueue<InfluxDatapoint<InfluxValueField>>()

在C#中，它可以毫无问题地进行编译，但是在F#中，我得到了:

in C#, it compiles without problem, but in F#, I get this:

[FS0001]类型'InfluxValueField'与类型'IComparable'不兼容

[FS0001] The type 'InfluxValueField' is not compatible with the type 'IComparable'

在canton7的评论之后，这是两个外部元素的来源:

Following the comment from canton7, here is the source for both external elements:

InfluxValueField: https://github .com/AdysTech/InfluxDB.Client.Net/blob/master/src/DataStructures/InfluxValueField.cs

InfluxValueField: https://github.com/AdysTech/InfluxDB.Client.Net/blob/master/src/DataStructures/InfluxValueField.cs

InfluxDataPoint: https://github .com/AdysTech/InfluxDB.Client.Net/blob/master/src/DataStructures/InfluxDatapoint.cs

InfluxDataPoint: https://github.com/AdysTech/InfluxDB.Client.Net/blob/master/src/DataStructures/InfluxDatapoint.cs

什么会导致它在C#中而不在F#中编译?

What could cause it to compile in C# but not in F#?

这是两个代码示例:

C#

namespace A
{
    using System.Collections.Concurrent;
    using AdysTech.InfluxDB.Client.Net;

    public class test
    {
        public test()
        {
            var Events = new ConcurrentQueue<InfluxDatapoint<InfluxValueField>>();
        }
    }
}

F#

namespace A

open System.Collections.Concurrent
open AdysTech.InfluxDB.Client.Net

    module B =
        let Events = new ConcurrentQueue<InfluxDatapoint<InfluxValueField>>()

推荐答案

此处的窍门是对接口进行编程，而不是对实现进行编程.因此，请使用接口作为通用类型参数，而不是具体类型.

The trick here is to program to interfaces instead of implementations. So use an interface as the generic type parameter, instead of a concrete type.

open AdysTech.InfluxDB.Client.Net
open System.Collections.Concurrent

let events = ConcurrentQueue<IInfluxDatapoint>()
let event1 = InfluxDatapoint<IInfluxValueField>()
let field1a = InfluxValueField(42.99)
let field1b = InfluxValueField("a message")
let event2 = InfluxDatapoint<IInfluxValueField>()
let field2a = InfluxValueField(0.05)

let addEvents () = 
    event1.Fields.Add("amountRequestedUSD", field1a)
    event1.Fields.Add("message", field1b)
    events.Enqueue(event1)
    event2.Fields.Add("someDouble", field2a)
    events.Enqueue(event2)

这篇关于声明中的C#/F#差异很奇怪，代码在C#中编译，但在F#中没有的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！