Using partial active patterns to return calculated data in pattern matches

du-with-partial-active-pattern.fs

/// Several types of consoles
type Console =
    | Playstation_5
    | Xbox_Series_X
    | Switch
with
    member this.Name =
        match this with
        | Playstation_5 -> "Playstation 5"
        | Xbox_Series_X -> "XBox Series X"
        | Switch -> "Switch"

type GpuDetails = { ComputeUnits:int; Shaders:int }
with
    /// AMD hardware has 64 shaders per compute unit
    static member Create (numCU:int) = { ComputeUnits = numCU; Shaders = 64 * numCU }

/// Active patterns can execute some additional code and output data on the match. 
/// Partial active patterns return an option for cases that don't "fit" the match.

/// Now a partial active pattern to show GPU details for consoles that have them
let (|GPU|_|) (console:Console) =
    match console with
    | Playstation_5 -> GpuDetails.Create 36 |> Some
    | Xbox_Series_X -> GpuDetails.Create 52 |> Some
    | Switch -> None // It has some GPU, but we don't have the details

/// Match for the GPU on all types of consoles, printing what GPU info we have available
for console in [ Xbox_Series_X; Playstation_5; Switch ] do
    match console with
    | GPU gpu -> Console.WriteLine $"{console.Name} has {gpu.ComputeUnits} compute units and {gpu.Shaders} shaders."
    | _ -> () // Nothing executed when we don't have GPU information.

XBox Series X has 52 compute units and 3328 shaders.
Playstation 5 has 36 compute units and 2304 shaders.