Hi everyone Initially, I hope that this list is active yet. For some days, I had been trying to do a Depth First Search on a graph from scratch following something very didactical (clear, elegant - legible, any worry about efficiency). This DFS keeps a boolean list to mark the nodes already visited and another with current or valid nodes ( the stack of DFS classic). The code is naive and well documented and is here: https://github.com/claudiosa/CCS/blob/master/haskell/dfs_graph.hs (excessively commented) but unfortunately, it is not working. My guess is that the problem starts on *new_node* function. I am not sure if in DFS, when a current node gets a next neighbour to stack, it gets all the neighbours. In this code, it is getting one node per time. The functions next_node and one_node seem very non-sense. Could someone help me? Thanks in advance claudio **************************************************************** ************ *Whatsapp: +55 47 992451825 <%2B55%2047%2092451825>* https://claudiocesar.wordpress.com/ (my links HERE) https://github.com/claudiosa https://www.udemy.com/picat-uma-linguagem-de-programacao-multiparadigma/ **************************************************************** *************