I need to build a function, which return all paths between certain nodes. connect :: Int -> Int-> [[(Int,Int)]] Data.Graph library gives me usefull function 'buildG' which builds graph for me. If I call let g = buildG (1,5) [(1,2),(2,3),(3,4),(4,5),(2,5)], I will get an array where every node is mapped to his neighbours. An example: g!1 = [2] g!2 = [3,5] .. g!5 = [] I was trying to do it using list comprehensions, but I am not very good in haskell and I am getting typing error which I can't repair. connect x y g | x == y = [] | otherwise = [(x,z) | z <- (g!x), connect z y g] I don't need to worry at this moment about cycles. Here is what I want to get: connect 1 5 g = [[(1,2),(2,3),(3,4),(4,5)],[(1,2),(2,5)]]