(\/) :: Series a -> Series a -> Series a
(a \/ b) d = C (SumOfProd (ssa ++ ssb)) (ca ++ cb)
  where
    C (SumOfProd ssa) ca = a d
    C (SumOfProd ssb) cb = b d
(\/) :: Series a -> Series a -> Series a
(a \/ b) d = C (SumOfProd (ssa ++ ssb)) (ca ++ cb)
  where
    C (SumOfProd ssa) ca = a d
    C (SumOfProd ssb) cb = b d
(\/) :: Series a -> Series a -> Series a
(a \/ b) d = C (SumOfProd (ssa ++ ssb)) (ca ++ cb)
  where
    C (SumOfProd ssa) ca = a d
    C (SumOfProd ssb) cb = b d