let decode (utf8: string) = 

    utf8.Split('\\')

    |> Array.mapi 

        (fun index s ->

            if index <> 0 

            then (+) "\\" s

            else s)

    |> Array.reduce (+)

decode "

\u03a1\u03bf\u03b6\u03bf\u03bd\u03b5\u03c1\u03af-

"

|> printfn "%s"