Hi John,
When I was first encountered replicateM I found it really hard to understand. So,of course, I am audacious enough to assume that it is hard for you too!

The code suggested by Brent ,  'replicateM 3 foo' is a nicer way of writing the following:

foo = do
  x <- getStdRandom $ randomR (1,10)
  y <- getStdRandom $ randomR (1,10)
  z <- getStdRandom $ randomR (1,10)
  return [x,y,z]

Hope this helped.
-deech

On Sat, Oct 24, 2009 at 7:05 PM, Brent Yorgey <byorgey@seas.upenn.edu> wrote:
On Sat, Oct 24, 2009 at 05:59:35PM +0100, John Moore wrote:
> Hi All,
>            Can anyone help me I want to produce a list of three random
> numbers for e.g. [7,8,1]
> I tried using x <- getStdRandom $ randomR (1,10) but don't really understand
> this and it only generates one number. Any help greatly appreciated.

replicateM is your friend:

 replicateM :: (Monad m) => Int -> m a -> m [a]

so if 'foo' produces a single random number, then 'replicateM 3 foo'
produces a list of three.

-Brent
_______________________________________________
Beginners mailing list
Beginners@haskell.org
http://www.haskell.org/mailman/listinfo/beginners