subsequences

subseq.hs

subseq :: Int ->[a]->[[a]]
subseq _ [] = []
subseq n xs | len_xs<n = []
			| len_xs==n = [xs]
			| otherwise = take n xs : subseq n (tail xs)
			where len_xs = length xs

subseq' :: Int ->[a]->[[a]]
subseq' n xs = filter (flip isInfixOf xs) (filter ( eq_len ) (subsequences xs) ) where eq_len ys = length ys == n


continuousSubSeqs = filter (not . null) . concatMap inits . tails