I've been working on a quick program that acts (vaguely) like a console, lets me type notes and outputs them in a .tex file. I figure it's not that complicated, but it uses a vaguely n-ary structure, so that I can have headers and sub-notes, which loos like: data Note = N { nTitle :: {Char}, nBody :: {Char}, nFormat :: Format, subs :: [Note] | E [Char] Format's just a collection of preset formats, so I don't have to dynamically handle that (since I didn't need to for my uses). Anyways, for whatever reason, sometimes while adding notes, it sends me an error: Prelude.(!!): index too large My only 2 uses of that are in getFullName :: [Note] -> [Int] -> [Char] getFullName d [] = "/" getFullName d (x:xs) = "/" ++ getPartName (d!!x) ++ getFullName (subs (d!!x)) xs and moveIn :: [Note] -> [Int] -> [Char] -> Int -> [Int] moveIn [] i m c = reverse i moveIn ((N dt db df du):ds) [] m c = if matchNote (N dt db df du) m then c:[] else moveIn ds [] m (c+1) moveIn n i m c = last i : ((moveIn (subs (n!!(last i)))) (allButLast i) m 0) where the [Int] is the variable I use to track where in the tree I am. Since I'm not moving into a Note that doesn't exist, and the display shouldn't be changing, what could be the problem? This is probably too in-depth a question, now that I think about it...