separate_list_by_contiguous_and_equal_elements.hs

-- Simple approach to grouping a list of items by being both contiguous and equal

-- The aim is to take a list of items, check each item sequentially to see if it is the same
-- as the last item.

-- Separates a list like this: [1,2,2,2,3,3,4,4,1,1,2,2] => [[1],[2,2,2],[3,3],[4,4],[1,1],[2,2]]

separate' :: Eq a => [a] -> Int -> [[a]]
separate' (x0 : xs@(x1 : _)) n
    | x0 == x1   = separate' xs (n + 1)
    | otherwise  = (replicate n x0):(separate' xs 1)
separate' (x:_) n = [(replicate n x)]

separate :: Eq a => [a] -> [[a]]
separate items = separate' items 1