Can someone provide a hand calculation of: span (< 0) [-1, -2, -3, 0, 1, 2, -3, -4, -5]? I know the result is ([-1, -2, -3], [0, 1, 2, -3, -4, -5]), but the recursion flummoxes me. Here's the Prelude definition: mySpan :: (a -> Bool) -> [a] -> ([a], [a]) mySpan _ [] = ([], []) mySpan p xs@(x:xs') | p x = (x:ys, zs) | otherwise = ([], xs) where (ys, zs) = mySpan p xs' Thanks. _________________________________________________________________ Hotmail has tools for the New Busy. Search, chat and e-mail from your inbox. http://www.windowslive.com/campaign/thenewbusy?ocid=PID28326::T:WLMTAGL:ON:W...