On 10/28/06, jim burton
I need to find the length of the longest in-sequence section of a list of ints...I am guessing something like mapAccumL is the way but not sure how.
--this doesn't work Prelude List> mapAccumL (\x y -> if y==(x+1) then (y, x) else (y,0)) 0 $ sort $ nub [9, 1, 2, 7, 3, 4, 5, 6,5] (9,[0,1,2,3,4,5,6,0])
I'm not sure I completely understand what you want, and if it needs to be "cute" (i.e. some clever one liner usage of a library function). But here's my "get-the-job-done-solution" (assuming I understood what you want): import Data.List import Data.Ord longestInSequence :: (Enum a) => [a] -> Int longestInSequence = maximum . map (length . takeInSeq) . tails takeInSeq [] = [] takeInSeq [x] = [x] takeInSeq (x:y:xs) | fromEnum (succ x) == fromEnum y = x : takeInSeq (y:xs) | otherwise = takeInSeq (x:xs) /S -- Sebastian Sylvan +46(0)736-818655 UIN: 44640862