I need to write an implementation using foldl, and a separate implementation using foldr, of a function, "remdups xs", that removes adjacent duplicate items from the list xs. For example, remdups [1,2,2,3,3,3,1,1]= [1,2,3,1]. My approach is first to write a direct recursion, as follows: remdups :: (Eq a) => [a] -> [a] remdups [] = [] remdups (x : []) = [x] remdups (x : xx : xs) = if x == xx then remdups (x : xs) else x : remdups (xx : xs) This code works, but it has three cases, not usual two, namely [] and (x : xs). What, if any, is the implementation using only two cases? Also, if three cases are required, then how can it be implemented using foldr, and how using foldl? Thanks. _________________________________________________________________ Express your personality in color! Preview and select themes for Hotmail®. http://www.windowslive-hotmail.com/LearnMore/personalize.aspx?ocid=TXT_MSGTX...