open System
open System.Globalization
open System.Collections

let seqOfEnumerator<'T> (e: IEnumerator) = seq {
    while e.MoveNext() do yield e.Current :?> 'T
}

let reverse (s: string) =
    s
    |> StringInfo.GetTextElementEnumerator
    |> seqOfEnumerator<string>
    |> Seq.rev
    |> String.concat ""

let display (s) =
  printfn "original: %s" s
  printfn "ok      : %s" (reverse s)
  printfn "naive   : %s" (s.ToCharArray() |> Array.rev |> System.String)

display "foo 𝌆 bar mañana mañana"
display "𠈓"
display "Les Mise\u0301rables"