you're not missing something, I believe the comment just got it flipped, and was referring[1] to problems relating to covariance and contravariance, when one tr

you're not missing something, I believe the comment just got it flipped, and was referring[1] to problems relating to covariance and contravariance, when one tries to view OOP in terms of type theory. [1] http://en.wikipedia.org/wiki/Covariance_and_contravariance_(computer_science)#Overview_of_covariance.2Fcontravariance_in_some_programming_languages http://en.wikipedia.org/wiki/Covariance_and_contravariance_(...