[Haskell-cafe] How to use Data.ByteString ?

Hi, friends the following function works well rollDice n = getStdRandom (randomR (1,n)) :: IO Int now i want to use /dev/random to produce better random number, but it doesnot work rollDice_t n = do hd <- openFile "/dev/random" ReadMode v <- B.hGet hd 1 return (v `mod` n) + 1 No instance for (Integral B.ByteString) arising from a use of `mod' at Money.hs:15:12-20 Possible fix: add an instance declaration for (Integral B.ByteString) In the first argument of `return', namely `(v `mod` n)' In the first argument of `(+)', namely `return (v `mod` n)' In the expression: return (v `mod` n) + 1 then how to use the ByteString properly ? Sincerely!