Hello, I'm sorry this is a very elementary question (but I am pulling my hair out). With a function written in ML: fun filter_list P [] = [] | filter_list P (h :: t) = let val ft = filter_list P t in if P h then (h :: ft) else ft end; OR fun member (e, nil) = false | member (e , (h :: t)) = if (e=h) then true else member (e, t) ; What is the preferred way to write in OCaml using pattern matching on parms?? Regards, Vasili --------------------------------- Do you Yahoo!? vote.yahoo.com - Register online to vote today!