Specify field order for CsvHelper when writing

gistfile1.cs

static void WriteCsv<T> (IEnumerable<T> data, string file, params string[] fields)
{
    var writerType = typeof (CsvWriter);
    var writerParam = Expression.Parameter (writerType, "writer");
    var itemType = typeof (T);
    var itemParam = Expression.Parameter (itemType, "item");

    var fieldWriters = new List<Action<CsvWriter, T>> ();
    foreach (var name in fields) {
        var value = Expression.PropertyOrField (itemParam, name);
        var writeMethod = Expression.Call (writerParam, "WriteField", new[] {value.Type}, value);
        var action = Expression.Lambda<Action<CsvWriter, T>> (writeMethod, writerParam, itemParam).Compile ();
        fieldWriters.Add (action);
    }

    using (var stream = new StreamWriter (file))
    using (var writer = new CsvWriter (stream)) {
        foreach (var name in fields) {
            writer.WriteField (name);
        }
        writer.NextRecord ();

        foreach (var item in data) {
            foreach (var write in fieldWriters) {
                write (writer, item);
            }
            writer.NextRecord ();
        }
    }
}