title: Haskell and random numbers
body: <p>I've been messing with Haskell few days and stumbled into a problem.</p>
  
  <p>I need a method that returns a random list of integers ( Rand [[Int]] ).</p>
  
  <p>So, I defined a type: <code>type Rand a = StdGen -&gt; (a, StdGen)</code>. 
  I was able to produce <code>Rand IO Integer</code> and <code>Rand [IO Integer]</code> ( <code>(returnR lst) :: StdGen -&gt; ([IO Integer], StdGen)</code> ) somehow. Any tips how to produce <code>Rand [[Int]]</code>?</p>