[Haskell-cafe] more improvable randomness

[Henning Thielemann]

On Thu, 8 Oct 2009, Michael Mossey wrote:

> I wrote some code to model the keystroke-to-keystroke delay in a person
> typing, with pseudorandomness. There are two kinds of delays.. one is a
> very small delay as the person reaches for a new key (call this 'reach'
> delays), the other is a larger delay that represents a pause to think or
> to take a break (call this 'break' delays).

Has this to do with your PortMidi problems?

> breakSeries :: Int -> Int -> StdGen -> [Float]
> breakSeries lowerB upperB gen =
>   let (n,gen1) = randomR (lowerB,upperB) gen
>       (gen2,gen3) = split gen1
>       delay = generate 1 gen2 breakM
>   in replicate n 0 ++ [delay] ++ breakSeries lowerB upperB gen3
>
> breakM :: Gen Float
> breakM = frequency [ (10, choose( 1::Float   ,  2))
>                   , (10, choose( 4::Float   ,  6)) ]
>
> test = (print . take 100 . breakSeries 2 4 ) =<< newStdGen

Gen is from QuickCheck package, isn't it? That can't be mixed with Random 
from 'random' package. You could wrap 'randomR' in a State monad 
('transformers' package), write your own 'frequency' function for that, 
and run that with the seed from 'newStdGen'.