http://fssnip.net/3U をMS Excel向けCSVに特化 (Not Tested!)

Csv.Fs

// http://fssnip.net/3U をベースとするCSV出力モジュール。
/// F#のSeqを拡張している。
/// 元ネタではセパレータを選べたが、その機能を殺してMicrosoft Excel向けCSVに特化した。
module Csv

open System.IO
open System.Text
open System.Text.RegularExpressions
open Microsoft.FSharp.Reflection

let csvEscape str =
// CSVのエスケープが必要な文字列表現を拾う正規表現
    let NeedCsvEscape str = Regex("(\"|'|,|\n|\r)",RegexOptions.Multiline).IsMatch(str)
    let tempstr = str.ToString()
    if (NeedCsvEscape tempstr) then 
            "\"" + tempstr.Replace("\"","\"\"") + "\""     
    else tempstr

type Array =
    static member join delimiter xs = 
        xs 
        |> Array.map (csvEscape)
        |> String.concat delimiter

type Seq =
    static member write (path:string) (data:seq<'a>): 'result = 
        use writer = new StreamWriter(path,false,Encoding.GetEncoding(932))
        data
        |> Seq.iter writer.WriteLine 

    static member csv (headerMapping:string -> string) ( data:seq<'a>) =
        let separator = ","
        seq {
            let dataType = typeof<'a>

            let header = 
                match dataType with
                | ty when FSharpType.IsRecord ty ->
                    FSharpType.GetRecordFields dataType
                    |> Array.map (fun info -> headerMapping info.Name)                    
                | ty when FSharpType.IsTuple ty -> 
                    FSharpType.GetTupleElements dataType
                    |> Array.mapi (fun idx info -> headerMapping(string idx) )
                | _ -> dataType.GetProperties()
                       |> Array.map (fun info -> headerMapping info.Name)

            yield header |> Array.join separator
                                    
            let lines =
                match dataType with 
                | ty when FSharpType.IsRecord ty -> 
                    data |> Seq.map FSharpValue.GetRecordFields
                | ty when FSharpType.IsTuple ty ->
                    data |> Seq.map FSharpValue.GetTupleFields
                | _ -> 
                    let props = dataType.GetProperties()
                    data |> Seq.map ( fun line -> 
                              props |> Array.map ( fun prop ->
                                prop.GetValue(line, null) ))                                     

            yield! lines |> Seq.map (Array.join separator)        
        }