The "Theorems for free" paper is here: http://ttic.uchicago.edu/~dreyer/course/papers/wadler.pdf http://ttic.uchicago.edu/~dreyer/course/papers/wadler.pdf ( I g

The "Theorems for free" paper is here: http://ttic.uchicago.edu/~dreyer/course/papers/wadler.pdf http://ttic.uchicago.edu/~dreyer/course/papers/wadler.pdf ( I guess is the most precise you can get :) )