group                   =  groupBy (==)

groupBy _  []=  []
groupBy eq (x:xs)=  (x:ys) : groupBy eq zs
                           where (ys,zs) = span (eq x) xs

span p [] = ([],[])
span p xs@(x:xs')
    | p x = (x:ys, zs)
    | otherwise = ([],xs)
        where (ys,zs) = span p xs'