Nice F# snippet! This just looks so simple and elegant. As another approach, the "enum" types the OP mentions map to discriminated unions in F#. FWIW your fin

Nice F# snippet! This just looks so simple and elegant. As another approach, the "enum" types the OP mentions map to discriminated unions in F#. FWIW your final wildcard match can be (modestly) simplified to just | _ -> num.ToString() and the last line can be distilled to just |> List.iter (printfn "%s")