A good example demonstrating this is the "reverse state monad" http://lukepalmer.wordpress.com/2008/08/10/mindfuck-the-reverse-state-monad/ http://lukepalmer.w

A good example demonstrating this is the "reverse state monad" http://lukepalmer.wordpress.com/2008/08/10/mindfuck-the-reverse-state-monad/ http://lukepalmer.wordpress.com/2008/08/10/mindfuck-the-reve... It sends state updates "back in time" to compute fixed points. The above article shows how you can compute the fibonacci stream using it.