[Haskell-beginners] integer to noise function in Haskell

I am trying to implement a basic pelin noise function, but I have some problem with the integer to noise function used to generate deterministic noise from integer inputs. the function I am trying to implement is defined there: http://libnoise.sourceforge.net/noisegen/index.html#continuousnoise and my code so far look like this: noise2d :: (Int32, Int32) -> Double noise2d (x, y) = let m = x + y * 57 n = (shiftR m 13) ^ m j = (n * (n * n * 15731 + 789221) + 1376312589) .&. 0x7fffffff in 1.0 - (fromIntegral j / 1073741824.0) the code compile but I get the same result for any input, due to the fact that n is evaluated to 0. Is there a better way to do that?