Andrew, Thanks for your detailed feedback, it is a great help. I appreciate that the code does not do anything useful, nor is it an appropriate way to write Haskell, but it does help me understand language constructs. I have seen statements like
data C3 c3 a => Address c3 a = Address c3 a
and wondered what they mean and how could they be used. I am studying the Haskell type class system as part of a language comparison. I am trying to exercise and understand the constructs rather than develop a meaningful application. Perhaps I should have mentioned this in my post. Thanks again, Pat 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