divide x y  = case divMod x y of
                (a,0) -> Just a
                _     -> Nothing

-- | Compute the exact root of a natural number.
-- The second argument specifies which root we are computing.
divide x y  = case divMod x y of
                (a,0) -> Just a
                _     -> Nothing

-- | Compute the exact root of a natural number.
-- The second argument specifies which root we are computing.
divide x y  = case divMod x y of
                (a,0) -> Just a
                _     -> Nothing

-- | Compute the exact root of a natural number.
-- The second argument specifies which root we are computing.