Hello, I am currently going through the CIS194 spring 13 course, since it has been recommended by several haskellions. I find the exercises extremely valuable, and the reading material is succinct (in a good way). I just finished the exercises for lesson two, and while everything works, I get this warning: Lektion02.hs:(38,1)-(44,21): warning: [-Wincomplete-patterns] … Pattern match(es) are non-exhaustive In an equation for ‘insert’: Patterns not matched: (LogMessage _ _ _) (Node _ (LogMessage _ _ _) _) I understand that there is a pattern I'm not covering, but I can't really figure out which one. Here is my function: insert :: LogMessage -> MessageTree -> MessageTree insert (Unknown _) mt = mt insert m Leaf = Node Leaf m Leaf insert m@(LogMessage _ t _) (Node left value@(LogMessage _ t' _) right) | t <= t' = Node (insert m left) value right | t > t' = Node left value (insert m right) insert m@(LogMessage _ _ _) (Node left (Unknown _) right) = Node left m right (here's a pastebin with intact indentation: http://lpaste.net/356716) I am not sure on how I should progress to find out which pattern I'm missing. Any help is appreciated. Kind regards, Jona