使用不区分大小写的比较从集合中减去记录 [英] Subtracting Records from a Set using case-insensitive comparison

问题描述

我有一组记录:

type Person =
    {
        Name : string
        Age : int
    }


let oldPeople =
    set [ { Name = "The Doctor"; Age = 1500 };
          { Name = "Yoda";       Age = 900 } ]

与上面的硬编码示例不同，数据集实际上来自数据源(对此我几乎没有控制权).现在，我需要从另一个数据源中减去一组数据.通常，第二个来源中的数据匹配，但偶尔在大小写上有所不同:

Unlike the hardcoded example above, the set of data actually comes from a data source (over which I have very little control). Now I need to subtract a set of data from another data source. In general, the data in this second source matches, but occasionally there is a difference in captialization:

let peopleWhoAreConfusedAboutTheirAge =
    set [ { Name = "THE DOCTOR"; Age = 1500 } ]

当我尝试从第一组减去第二组时，由于字符串比较区分大小写，所以它失败了:

When I attempt to subtract the second set from the first, it fails because the string comparison is case sensitive:

let peopleWhoKnowHowOldTheyAre =
    oldPeople - peopleWhoAreConfusedAboutTheirAge

val peopleWhoKnowHowOldTheyAre : Set<Person> =
  set [{Name = "The Doctor";
        Age = 1500;}; {Name = "Yoda";
                       Age = 900;}]

是否可以对People记录的Name字段执行不区分大小写的比较?

Is there a way to perform a case-insensitive comparison for the Name field of the People record?

推荐答案

这是另一种方法:

type Name(value) =
  member val Value = value
  override this.Equals(that) =
    match that with 
    | :? Name as name -> StringComparer.CurrentCultureIgnoreCase.Equals(this.Value, name.Value)
    | _ -> false
  override this.GetHashCode() =
    StringComparer.CurrentCultureIgnoreCase.GetHashCode(this.Value)

type Person =
  {
    Name: Name
    Age: int
  }

{Name=Name("John"); Age=21} = {Name=Name("john"); Age=21} //true

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