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 _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
