gistfile1.hs

data State = State {
      density :: Grid
    , previousDensity :: Grid
    , velocity :: (Grid,Grid)
    , previousVelocity :: (Grid,Grid)
    , mousePoint :: IORef (Int,Int)
    , oldMousePoint :: IORef (Int,Int)
    , leftDown :: IORef Bool
    , rightDown :: IORef Bool
    , drawVel :: IORef Bool
}