I would recommend Ralf Hinze's ICFP00 Pearl
Deriving Backtracking Monad Transformers
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.34.4164
He starts with a monad transformer expressed as a free term algebra,
and shows step-by-step how to transform it to a more efficient
context-passing style. He deals with exceptions and backtracking
rather than IO; the ideas are quite similar though.
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
