F# 将 int 数组选项连接到字符串

Question

我有一个数据协定 (WCF)，其字段定义为：

[<DataContract(Namespace = _Namespace.ws)>]
type CommitRequest =
{
// Excluded for brevity
...
[<field: DataMember(Name="ExcludeList", IsRequired=false) >]
ExcludeList : int array option
}

我想从 ExcludeList 中的条目创建一个逗号分隔的字符串（以减少到数据库的网络跳数以更新状态）。我尝试了以下两种方法，都没有创建所需的字符串，都是空的：

// Logic to determine if we need to execute this block works correctly
try
   //  Use F# concat
   let strList = request.ExcludeList.Value |> Array.map string
   let idString = String.concat ",", strList
   // Next try using .NET Join
   let idList = String.Join ((",", (request.ExcludeList.Value.Select (fun f -> f)).Distinct).ToString ())
with | ex -> 
  ...

编译和执行都没有给我任何字符串。非常感谢有人指出我在这里做错了什么。

Answer 1

let intoArray : int array option = Some [| 1; 23; 16 |]
let strList = intoArray.Value |> Array.map string
let idString = String.concat "," strList // don't need comma between params
// Next try using .NET Join
let idList = System.String.Join (",", strList) // that also works

输出：

> 
val intoArray : int array option = Some [|1; 23; 16|]
val strList : string [] = [|"1"; "23"; "16"|]
val idString : string = "1,23,16"
val idList : string = "1,23,16"

F# 将 int 数组选项连接到字符串

F# concatenate int array option to string

arrays

f#