absDiff :: Num a => [a] -> [a]
absDiff xs = do {(fst , snd) <- (help xs); return (abs(fst - snd))}
help xs = if (length xs >= 2) then make_pair 0 xs else []
make_pair i (fst:snd:xs) = if (length xs == 0) then [(fst, snd)] else [(fst, snd)]++ (make_pair (i+1) (snd:xs))