The author of the linked paper, Philip Wadler, is just phenomenal.<p><a href="http://homepages.inf.ed.ac.uk/wadler/" rel="nofollow">http://homepages.inf.ed.ac.uk/wadler/</a><p>><i>"I was a principal designer of Haskell. With Simon Marlow, I developed
a type tool for Erlang. I am a founding member of IFIP WG 2.8 Functional
Programming, and served as editor-in-chief of the Journal of Functional
Programming."</i>