Gabriel Gonzalez: The functor design pattern http://www.haskellforall.com/2012/09/the-functor-design-pattern.html http://www.haskellforall.com/2012/09/the-func

Gabriel Gonzalez: The functor design pattern http://www.haskellforall.com/2012/09/the-functor-design-pattern.html http://www.haskellforall.com/2012/09/the-functor-design-patt... is also a well-known post.