[Haskell-beginners] IO ( stuff )

[Isaac Dupree]

On 12/09/2011 05:27 PM, Brent Yorgey wrote:
> On Fri, Dec 09, 2011 at 05:05:15PM -0500, David McBride wrote:
>>
>> randomMonster :: RandomGen g =>  Rand g Monster
>> randomMonster = do
>>    x<- getRandomR (0,2::Int)
>>    return $ case x of
>>      0 ->  Orc
>>      1 ->  Dragon
>>      2 ->  Wolf
>
> This looks like a bug to me.  Everyone knows orcs are much more likely
> than dragons. ;)

I once wrote a function something like
randomDistributed :: (Num a, RandomGen g) => [(a, b)] -> g -> (b, g)

so that e.g.
randomDistributed [(10, Orc), (1, Dragon), (3.7, Wolf)]
would get you ten orcs for every dragon on average,
the overall chance of an orc being (10 / (10 + 1 + 3.7)).

~Isaac