CreateUnionValues.fsx

/// An example union.
type Team = Tottenham | Spurs | THFC

module Lists =
    open FSharp.Reflection

    /// Creates an array of all cases of a given union 'T.
    let makeAll<'T> =
        FSharpType.GetUnionCases typeof<'T>
        |> Array.map(fun info -> FSharpValue.MakeUnion(info, Array.empty) :?> 'T)

    /// All Team cases - calculated once
    let Teams = makeAll<Team>

type Team with
    /// For added ease of use, you could add this static extension member onto Team
    static member All = Lists.Teams

let allTeams = Lists.Teams
let allTeamsAgain = Team.All