F# 实现接口，多个参数，出现错误此覆盖需要不同数量的

Question

我在 F# 中定义了以下接口，

[<ServiceContract>]
type ICarRentalService =
    [<OperationContract>]
    abstract member CalculatePrice: pickupDate:DateTime -> returnDate:DateTime -> pickupLocation:string -> vehiclePreference:string -> float

然后尝试像这样实现它：

type CarRentalService() =
    interface ICarRentalService with
        override this.CalculatePrice(pickupDate:DateTime, returnDate:DateTime, pickupLocation:string, vehiclePreference:string) =
            5.5

编译时出现以下编译错误：

This override takes a different number of arguments to the corresponding abstract member

我现在正在查看这个东西并摆弄了一个小时，我做错了什么？

Answer 1

接口中的方法以柯里化形式声明，并且您的实现是元组的：
简而言之：接口中的方法是接受一个参数并返回另一个带有剩余参数的函数的函数。在相反的实现中，接受一个片段中的所有参数（打包在元组中）

open System
type ICarRentalService =
    abstract member CalculatePrice: pickupDate:DateTime -> returnDate:DateTime -> pickupLocation:string -> vehiclePreference:string -> float

let x : ICarRentalService = failwith "not implemented"
let a = x.CalculatePrice // DateTime -> DateTime -> string -> string -> float
let y = a (DateTime.Now) // DateTime -> string -> string -> float (first argument is bound)

要修复代码，您需要使实现柯里化或声明 - 元组。柯里化版本不适用于 WCF，因此请考虑使用元组版本

type ICarRentalService =
    abstract member CalculatePrice: pickupDate:DateTime * returnDate:DateTime * pickupLocation:string * vehiclePreference:string -> float

type CarRentalService() =
    interface ICarRentalService with
        override this.CalculatePrice(pickupDate:DateTime, returnDate:DateTime, pickupLocation:string, vehiclePreference:string) =
            5.5