Hello Paul, Wednesday, August 03, 2005, 12:03:49 AM, you wrote: PM> One thing I haven't found a really good discussion of, is practical PM> examples of building monads. There's plenty of discussion of the IO i recall one more usage of monads - to do parsing. read the following: http://www.cs.nott.ac.uk/~gmh//pearl.pdf http://www.cs.nott.ac.uk/~gmh//pearl.hs that is really beatiful - parsing monad used both for holding state (position in input stream) and to backtrack to alternative rules when parsing with current rule fails. these ideas also used in ParseC (parser combinators) library, which are widely used (read http://www.cs.uu.nl/people/daan/download/parsec/parsec.html) btw, just obstacles with creating more advanced parsing libraries with help of monads lead to inventing of arrows - more generalized variant of monads (see http://www.cs.chalmers.se/~rjmh/Papers/arrows.pdf) ps: another example can be CPS (continuation passing style) monads, but i know nothing about it, except for name :) may be someone can point me to tutorial? :) -- Best regards, Bulat mailto:bulatz@HotPOP.com