-- Compute a better value:
improve y x = (y + x/y) / 2

-- iteration:
iter y x = if ok y x then y else iter (improve y x) x

-- is the value ok?
ok y x = abs (y*y - x) < 0.001

sqrootUgly x = iter 1 x

-----------------------------------------------------------------

sqroot x = iter 1
 where
  -- Compute a better value:
  improve y = (y + x/y) / 2
  
  -- iteration:
  iter y = if good y then y else iter (improve y)
  
  -- is the value ok?
  good y = abs (y*y - x) < 0.001

  f True = x


-----------------------------------------------------------------
-- Number of elements in a list:
len :: [Int] -> Int
len []     = 0
len (x:xs) = 1 + len xs