F＃ - 最新列表到连接的字符串由间隔 [英] F# - Breaking a List into Concatenated Strings by an Interval

问题描述

我的电子邮件地址列表，我需要发送电子邮件通知到每个地址。我想在同一时间做到这一点的25个地址块。是否有一个函数式语言如F＃为折叠（串连）25电子邮件地址在一起......每个用分号隔开任何快捷方式。我知道有在.NET中的String.Split方法，但我需要Concat的25的时间。

I have a list of email addresses, and I need to send an email notification to each address. I'd like to do this in blocks of 25 addresses at a time. Is there any quick way in a functional language like F# to "fold" (concatenate) 25 emails addresses together... each separated by a semicolon. I know there is the String.Split method in .NET, but I need to concat 25 at a time.

什么是最优雅的方式来在F＃中执行此？

What is the most elegant way to perform this in F#?

推荐答案

如果这仍然是相关的，这里是一个功能的加入使用的分隔符，但没有转换为字符串数组的序列。

If this is still relevant, here is a function to join a sequence of strings using delimiter but without conversion to array.

open System
open System.Text

/// Join a sequence of strings using a delimiter.
/// Equivalent to String.Join() but without arrays.
let join (items : seq<string>) (delim : string) =
    // Collect the result in the string builder buffer
    // The end-sequence will be "item1,delim,...itemN,delim"
    let buff = 
        Seq.fold 
            (fun (buff :StringBuilder) (s:string) -> buff.Append(s).Append(delim)) 
            (new StringBuilder()) 
            items

    // We don't want the last delim in the result buffer, remove
    buff.Remove(buff.Length-delim.Length, delim.Length).ToString()

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