Thank you everybody for your responses, I am going to print them out and study them hard, particularly the use of left folds. I think I skipped that in RWH book... .I need to go back and re-cover the basic again I think... it's a tendency of mine to graze through stuff picking up what I need and sometimes you just can't beat learning the basics. As a still beginner after about eight months of (somewhat intermittent) usage I would say that in order to truly get to grips with Haskell as a concept let alone a language you need to know and understand ... * currying, which helped me to truly understand the signature notation used, a -> b -> c etc. I have used haXe, which is written in ocaml, and the notation is the same but now makes more sense! * function composition leading to point-less notation, this is better understood the currying penny has dropped * lazy versus strict evaluation and the concept of lazy I/O and why it can sometimes leave you scratching your head for a while!! LMAO! :) * monads: of course, for me the best video I've seen is this one. As a reluctant Drupal/PHP developer and wannabe FP developer for about six years now, each time I find myself coding some rubbish or other in PHP I have lots of 'ahah!' moments as I think that it would be nice to be able to express some idiom or form more succinctly in PHP and then I realise what X Y or Z is for in Haskell... that's the upside, the downside is I then have to continue the job in PHP! Thanks again, Sean.