So, pursuient to discussion on the various other haskell lists and some talk about DData recently, I was wondering whether adding an ordered list type might be useful. Often, when one knows a list is ordered, many algorithms (like building a tree-based set, or a map) become more efficient, however it is up to the programmer to ensure an ordered list is used where one is expected or obscure bugs might occur. I was thinking... (off the top of my head) module Data.OrdList(OrdList,toList,fromList,unsafeFromAscList) where newtype Ord a => OrdList a = OrdList { toList :: [a] } fromList = OrdList . sort unsafeFromAscList xs = OrdList xs with some appropriate instances which make an OrdList behave pretty much exactly like a list, except maintaining the ordered invarient... then we can safely convert between the various container types in O(n) time without the posibility of messing up... comments? where is the current proposed DData library anyway? John -- John Meacham - ⑆repetae.net⑆john⑈