Haskell and random numbers

Question

I\'ve been messing with Haskell few days and stumbled into a problem.

I need a method that returns a random list of integers ( Rand [[Int]] ).

So, I defined a ty

Answer 1

Using monadic notation, you should be able to write something like

randomList gen = do
    randomLength <- yourRandomInteger
    loop gen (randomLength + 1)
 where
    loop gen 1 = gen
    loop gen n = do { x <- gen; xs <- loop gen (n - 1); return (x:xs) }

And with this

randomInts :: Rand [Int]
randomInts = randomList yourRandomInteger

randomLists :: Rand [[Int]]
randomLists = randomList randomInts

Concerning the monadic computations itself, take a look at this article. Note that random generators are pure, you shouldn't need any IO just for this purpose.