Rejigger Num instance

[goldfirere]

It might be better to have

deriving instance (d ~ '[], Num d) => Num (Qu d l n)

or something similar to get better inference.

[nushio3]

Sure! That would broaden the places where we can use Num operators without signagures.

Would that be

deriving instance (Normalize d ~ '[], Num d) => Num (Qu d l n)

?