Maybe they're referring to this? https://en.wikibooks.org/wiki/Haskell/Lenses_and_functional_references https://en.wikibooks.org/wiki/Haskell/Lenses_and_functio

Maybe they're referring to this? https://en.wikibooks.org/wiki/Haskell/Lenses_and_functional_references https://en.wikibooks.org/wiki/Haskell/Lenses_and_functional_... As for the "abstract specification", I interpret it as decoupling the view from the model too, but maybe expressing how you can represent the model? Like "option" being representable by a dropdown or radius buttons. I don't know, I agree it's vague.