[Haskell-beginners] random

[aditya siram]

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 at 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
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