How to "compress" similar branches in comparison with the F # sample

Question

I have the following code:

    match intersection with
    | None ->
        printfn "Please provide an empty intersection for ring placement"
        gameState
    | Some x ->
        match x.Status with
        | Empty ->
            let piece = { Color = gameState.Active.Color; Type = Ring }
            putPieceOnIntersection gameState.Board pos piece

            printfn "%s ring placed at %A" (colorStr gameState.Active.Color) pos

            // Decide if we ended this phase
            let updatedPhase = if ringsPlaced = 10 then Main else Start(ringsPlaced + 1)
            let newActivePlayer = gameState.Players |> Array.find (fun p -> p.Color = invertColor gameState.Active.Color)
            let updatedGameState = { gameState with Active = newActivePlayer; CurrentPhase = updatedPhase }

            updatedGameState
        | _ ->
            printfn "Please provide an empty intersection for ring placement"
            gameState

As you can see, if the intersection of the variables is either None, or its status is different from empty, I have to do exactly the same branch of printing some text and return. However, I do not know how to make such a condition expression in F # so that I can split a single branch. In imperative programming, I would do it easily, but in F #, how can I do this?

thank

Answer 1

If Statusis a record field, you can do:

match intersection with
| Some { Status = Empty } ->
    // Code for empty...
| _ ->
    printfn "Please provide an empty intersection for ring placement"
    gameState

Otherwise, you can use protection:

match intersection with
| Some x when x.Status = Empty ->
    // Code for empty...
| _ ->
    printfn "Please provide an empty intersection for ring placement"
    gameState