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

It used to be that an instance of Num was also an instance of Show and Eq , but that's no longer the case.

You'll need to add a Show constraint as well.