Proposal: Num instance for (a -> b)

relevant reddit comment thread: https://www.reddit.com/r/haskell/comments/9vtis5/the_universe_of_discourse_i... instance Num b => Num (a -> b) where f + g = \x -> f x + g x f * g = \x -> f x * g x f - g = \x -> f x - g x negate f = \x -> negate (f x) abs f = \x -> abs (f x) signum f = \x -> signum (f x) fromInteger i = \x -> fromInteger (f x)