Hi Below is a class that I wish to create some instances of. I do not wish to change the class definition. It is supposed to represent containers of type x that contain things of type y. My attempt at the insert function seems ok for Char and lists, but not ok for Integer. How do I instantiate this class for integers and lists? Does this class definition permit y to be a list and hence x to be a list of lists? Something like: instance Containers [] [] where .. Is this a constructor class? Thanks, Pat class Containers x y where insert :: y -> x y -> x y remove :: y -> x y -> x y whatsIn :: x y -> [y] instance Containers [] Char where insert y [] = y:[] insert y m = y:m instance Containers [] Integer where insert y [] = y:[] insert y m = y:m -- OK -- insert '1' ['u','u','l','i'] -- Not OK -- insert 2 [9,2] This message has been scanned for content and viruses by the DIT Information Services E-Mail Scanning Service, and is believed to be clean. http://www.dit.ie