SaveCsv doesn't handle DateTimeOffset properly

[mweerden]

The following code from FrameUtils.fs (lines 314-316) is where the problem is:

    formatter (fun (dt:System.DateTimeOffset) ->
      if dt.TimeOfDay = TimeSpan.Zero then dt.Date.ToString("d", ci)
      else dt.DateTime.ToString(ci)) ] |> dict

Here dt.DateTime does not have the offset information, which will result in ToString just assuming the local time zone when required.

The other case is also not right, as the output will normally not include the offset with "d".

It's probably best to just use formatter (fun (dt:System.DateTimeOffset) -> dt.ToString(ci)) instead. (Personally, I would do the same for DateTime.)