Haskell why does “Num x” require “Show x”?

Question

Recently I took a look at Haskell, using LYAH.

I was messing around with type classes and wrote this quick test function:

foo :: (Num x) => x ->         


        

Answer 1

Shouldn't you write:

(Num x) => x -> String

Instead of

(Num x) x -> String

And as far as I know this inheritance is at least outdated.