Re: [Haskell-cafe] "Natural" polymorphism for n*(n+1)/2

On Wed, 16 Dec 2020, Tom Smeding wrote:

You say 'abs x = x/2', but what's that (/)? For example, what is 'abs' supposed to give when called on (the representation of) the polynomial X^2 + 3X + 2?

I meant it this way: instance (Fractional a) => Num (Polynomial a) where abs = fmap (/2)