I seem to still be missing some things. I found mt19937 in GSL.Random.Gen, but there are two evalMCs, one in Control.Monad.MC and another in Control.Monad.MC.GSL. Which?

Michael

---------

Registering monte-carlo-0.4.1...

Installing library in /home/michael/.cabal/lib/monte-carlo-0.4.1/ghc-7.0.2

Registering monte-carlo-0.4.1...

[michael@sabal ~]$ ghci

GHCi, version 7.0.2: http://www.haskell.org/ghc/ :? for help

Loading package ghc-prim ... linking ... done.

Loading package integer-gmp ... linking ... done.

Loading package base ... linking ... done.

Prelude> :m + Control.Monad.MC.Class

Prelude Control.Monad.MC.Class> evalMC (sampleSubset [1..20] 5) (mt19937 0)

<interactive>:1:1: Not in scope: `evalMC'

<interactive>:1:34: Not in scope: `mt19937'

Prelude Control.Monad.MC.Class>

--- On Mon, 6/13/11, Felipe Almeida Lessa <felipe.lessa@gmail.com> wrote:

From: Felipe Almeida Lessa <felipe.lessa@gmail.com>
Subject: Re: [Haskell-cafe] Acquiring a random set of a specific size (w/o dups) from a range of Ints
To: "michael rice" <nowgate@yahoo.com>
Cc: haskell-cafe@haskell.org
Date: Monday, June 13, 2011, 9:38 PM

On Mon, Jun 13, 2011 at 8:56 PM, michael rice <nowgate@yahoo.com> wrote:
> Is there an (existing) way to select 5 Ints randomly (no duplicates) from a population, say 1-20 (inclusive)?

Yes, already implemented in the monte-carlo package as sampleSubset [1],

sampleSubset :: MonadMC m => [a] -> Int -> m [a]

Complete example code for your example:

evalMC (sampleSubset [1..20] 5) (mt19937 0)

Cheers!

[1] http://hackage.haskell.org/packages/archive/monte-carlo/0.4.1/doc/html/Control-Monad-MC-Class.html#v:sampleSubset

--
Felipe.