Active Pattern sample from F#, THIS AINT A GAME by ANDREA MAGNORSKY http://www.roundcrisis.com/presentations/fsharp_this_aint_a_game/index.html#/

ActivePattern01.fsx

let (|SpaceKey|) (keyboard:KeyboardInput) = 
    keyboard.KeyPressed(Key.Space)

let (|Hold100ms|) (keyboard:KeyboardInput) = 
    keyboard.KeyPressedFor(Key.I, 100)  

match DualityApp.Keyboard with        
| SpaceKey true & Hold100ms false -> playerGo Jump
| SpaceKey true & Hold100ms true -> playerGo DoubleJump

ActivePattern02.fsx

let (|LeftKey|RightKey|OtherKey|) (keyboard:KeyboardInput) = 
    if keyboard.KeyPressed(Key.Left) then LeftKey
    elif keyboard.KeyPressed(Key.Right) then RightKey
    else OtherKey "Hi, you pressed a key...well that is interesting :D"

interface ICmpUpdatable with
    member this.OnUpdate()=        
        match DualityApp.Keyboard with            
        | LeftKey  -> playerGo Left
        | RightKey-> playerGo Right
        | OtherKey s-> ()