normaliseExp :: (Ord v, Ord c) => SOP v c -> SOP v c -> SOP v c
-- b^1 ==> b
normaliseExp b (S [P [I 1]]) = b
normaliseExp :: (Ord v, Ord c) => SOP v c -> SOP v c -> SOP v c
normaliseExp b (S [P [I 1]]) = b
normaliseExp b (S [P [I 1]]) = b