fsharpcases.fs

    let lookupImageKey = function
    | EntityType.Laser _ -> Laser
    | EntityType.Bullet _ -> Bullet
    | _ -> LargeInvaderOpen

    let lookupImage imageKey = Map.tryFind imageKey lookupTable

    let positionImage image entity =
        match entity with 
        | EntityType.Laser e -> {Image = image; 
                                 Position = {X = e.Entity.Position.X; 
                                             Y = e.Entity.Position.Y}}
        | EntityType.Bullet e -> {Image = image; 
                                 Position = {X = e.Entity.Position.X; 
                                             Y = e.Entity.Position.Y}}
        | _ -> {Image = image; Position = {X = 0.; Y = 0.}}