(F# versus. C#) Print all file paths in both top level directories and sub directories.

Program.cs

using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace ConsoleApplication9
{
    class Program
    {
        static void Main()
        {
            using (var writer = new StreamWriter("C:\\Users\\ByteBlast\\Desktop\\dump.txt"))
            {
                foreach (var file in AllFilesUnder("M:/othr"))
                    writer.WriteLine(file);
            }
        }

        static IEnumerable<string> AllFilesUnder(string basePath)
        {
            foreach (var file in Directory.GetFiles(basePath))
                yield return file;

            foreach (var x in Directory.GetDirectories(basePath).Select(AllFilesUnder).SelectMany(files => files))
                yield return x;
        }
    }
}

Program.fs

open System.IO;

let rec allFilesUnder basePath =
    seq {
        yield! Directory.GetFiles(basePath)

        for subdir in Directory.GetDirectories(basePath) do
            yield! allFilesUnder subdir
    }

[<EntryPoint>]
let main args =
    use writer = new StreamWriter("C:\\Users\\ByteBlast\\Desktop\\dump.txt")
    (allFilesUnder "M:/othr") |> Seq.iter writer.WriteLine
    0