Hi Mitar,
I have made this function to generate a random graph for Data.Graph.Inductive library:
generateGraph :: Int -> IO (Gr String Double) generateGraph graphSize = do when (graphSize < 1) $ throwIO $ AssertionFailed $ "Graph size out of bounds " ++ show graphSize let ns = map (\n -> (n, show n)) [1..graphSize] es <- fmap concat $ forM [1..graphSize] $ \node -> do nedges <- randomRIO (0, graphSize) others <- fmap (filter (node /=) . nub) $ forM [1..nedges] $ \_ -> randomRIO (1, graphSize) gen <- getStdGen
Others have already remarked that you could implement this as a pure function. However, the mistake is the use of getStdGen here, which is (almost?) never what you need: two consecutive valls of getStdGen will return the same generator. You should call newStdGen instead. Best regards, Bertram