Hi folks. I was teaching a colleague about Monoids...

# arrow

[Leandro Borges Ferreira]

Hi folks.
I was teaching a colleague about Monoids and I was looking for an example like this:

@instance(SomeClass::class)
interface SomeClassMonoid : Monoid<SomeClass> {
    override fun empty(): SomeCalss = SomeCalss(someStuff)

    override fun VirtualCard.combine(b: VirtualCard): VirtualCard = away to combine then
}

But I couldn't find it.

Also I think that it would be nice the show an example using `List`'s fold with Monoids before showing one using `Foldable`'s foldmap. I would like to create a PR with some changes in the documentation.
Would that be ok?