I read about this concept before, I think here: https://typelevel.org/blog/2016/09/19/variance-phantom.html https://typelevel.org/blog/2016/09/19/variance-phant

I read about this concept before, I think here: https://typelevel.org/blog/2016/09/19/variance-phantom.html https://typelevel.org/blog/2016/09/19/variance-phantom.html