curb :: Ord a => a -> a -> a -> a
curb l h x
  | x < l     = l
  | x > h     = h
  | otherwise = x
curb :: Ord a => a -> a -> a -> a
curb l h x
  | x < l     = l
  | x > h     = h
  | otherwise = x
curb l h x
  | x < l     = l
  | x > h     = h
  | otherwise = x