gistfile1.hs

-- |A simple loop over each pixel
forEachPixel :: Grid -> ((Int,Int) -> IO()) -> IO()
forEachPixel (Grid n _) = forM_ [(u,v) | u<-[1..n], v <- [1..n]]

-- |For simplicity, just consider up,down,left,right to be the neighbours
neighbours :: Grid -> (Int,Int) -> IO (Double,Double,Double,Double)
neighbours g (x,y) = do 
  up <- readVal g (x-1,y)
  down <- readVal g (x+1,y)
  left <- readVal g (x,y-1)
  right <- readVal g (x,y+1)
  return (up,down,left,right)