This is an old revision of the document!

Random values

example

code, module Main:

{-# OPTIONS_GHC -fno-warn-orphans #-}
 
import qualified Randomisable as Rnd
 
main :: IO ()
main = do
  prng0 <- Rnd.newStdGen
  print $ processMyData ((Rnd.random prng0) :: MyData)
  print $ processMyData ((Rnd.random prng0) :: MyData)
 
processMyData :: MyData -> (MyData, MyData, MyData2, ScaleA)
processMyData (MyData prng0 nd1 nd2 mydt2) = 
    let
        (prng1, prng2, prng3, prng4, prng5) = Rnd.tplPrngSplit5 prng0
    in
        ((MyData prng1 nd1 nd2 mydt2), (MyData prng2 (Rnd.randomise prng3 nd1) nd2 mydt2), ((Rnd.random prng4) :: MyData2), ((Rnd.random prng5) :: ScaleA))
 
data MyData = MyData Rnd.StdGen Double Double MyData2
    deriving (Show, Read)
 
data MyData2 = MyData2 Double Double
    deriving (Show, Read)
 
newtype ScaleA = ScaleA Double
    deriving (Show, Read)
 
instance Rnd.Randomisable ScaleA where
    randomS = (Rnd.randomValueS (0.0, 2.0)) >>= (\d -> return (ScaleA d))
 
instance Rnd.Randomisable Double where
    randomS = Rnd.randomValueS (0.0, 1.0)
    randomiseS n = Rnd.randomiseValueProbablyS 0.1 (0.0, 1.0) n
 
instance Rnd.Randomisable MyData2 where
    randomS = 
        do
            r1 <- Rnd.randomS
            r2 <- Rnd.randomS
            return (MyData2 r1 r2)
 
instance Rnd.Randomisable MyData where
    randomS = 
        do
            prng1 <- Rnd.splitGenS
            r1 <- Rnd.randomS
            r2 <- Rnd.randomS
            r3 <- Rnd.randomS
            return (MyData prng1 r1 r2 r3)

code, module Randomisable:

{-# LANGUAGE FlexibleInstances, ScopedTypeVariables #-}
 
module Randomisable (
        Randomisable(..), 
        Rnd.Random, 
        Rnd.StdGen, 
        randomValueS, 
        randomListS, 
        randomiseValueProbablyS, 
        getGenS, 
        splitGenS, 
        tplSplitGenS2, 
        tplSplitGenS3, 
        tplSplitGenS4, 
        tplSplitGenS5, 
        tplSplitGenS6, 
        tplSplitGenS7, 
        tplSplitGenS8, 
        tplSplitGenS9, 
        lPrngSplit, 
        splitPrng, 
        tplPrngSplit2, 
        tplPrngSplit3, 
        tplPrngSplit4, 
        tplPrngSplit5, 
        tplPrngSplit6, 
        tplPrngSplit7, 
        tplPrngSplit8, 
        tplPrngSplit9, 
        Rnd.newStdGen
    ) where
 
import qualified System.Random as Rnd
import qualified Control.Monad.State as S
 
--import Debug.Trace
trace :: String -> a -> a
trace _ = id
 
class Randomisable r where
    random :: Rnd.StdGen -> r
    random prng = S.evalState randomS prng
    randomS :: S.State Rnd.StdGen r
    randomise :: Rnd.StdGen -> r -> r
    randomise prng r = S.evalState (randomiseS r) prng
    randomiseS :: r -> S.State Rnd.StdGen r
    randomiseS x = return x
 
randomValueS :: Rnd.Random a => (a, a) -> S.State Rnd.StdGen a
randomValueS range = S.state (Rnd.randomR range)
 
randomiseValueProbablyS :: Rnd.Random a => Double -> (a, a) -> a -> S.State Rnd.StdGen a
randomiseValueProbablyS ndPrb rng nValue0 = 
    do
        ndDice <- randomValueS (0.0, 1.0)
        if ndDice < ndPrb
            then (randomValueS rng)
            else (return nValue0)
 
randomListS :: forall a . Randomisable a => Integer -> S.State Rnd.StdGen [a]
randomListS nPopulation = (trace "randomListS tp#1" $ randomListS' nPopulation [])
    where
        randomListS' :: forall b. Randomisable b => Integer -> [b] -> S.State Rnd.StdGen [b]
        randomListS' nPopulation' lgntyp 
            | nPopulation' > 0 = 
                do
                    r1 <- (trace "randomListS' tp#1 " $ randomS)
                    result <- (trace ("randomListS' tp#2 nPopulation'=" ++ (show nPopulation')) $ (randomListS' (nPopulation' - 1) (r1 : lgntyp)))
                    (trace "randomListS' tp#3" $ return result)
            | otherwise       = (trace "randomListS' tp#4" $ return lgntyp)
 
getGenS :: S.State Rnd.StdGen Rnd.StdGen
getGenS = S.gets id
 
splitGenS :: S.State Rnd.StdGen (Rnd.StdGen)
splitGenS = 
    do
        prng <- getGenS
        return (splitPrng prng)
 
tplSplitGenS2 :: S.State Rnd.StdGen (Rnd.StdGen, Rnd.StdGen)
tplSplitGenS2 = 
    do
        prng <- getGenS
        return (tplPrngSplit2 prng)
 
tplSplitGenS3 :: S.State Rnd.StdGen (Rnd.StdGen, Rnd.StdGen, Rnd.StdGen)
tplSplitGenS3 = 
    do
        prng <- getGenS
        return (tplPrngSplit3 prng)
 
tplSplitGenS4 :: S.State Rnd.StdGen (Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen)
tplSplitGenS4 = 
    do
        prng <- getGenS
        return (tplPrngSplit4 prng)
 
tplSplitGenS5 :: S.State Rnd.StdGen (Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen)
tplSplitGenS5 = 
    do
        prng <- getGenS
        return (tplPrngSplit5 prng)
 
tplSplitGenS6 :: S.State Rnd.StdGen (Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen)
tplSplitGenS6 = 
    do
        prng <- getGenS
        return (tplPrngSplit6 prng)
 
tplSplitGenS7 :: S.State Rnd.StdGen (Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen)
tplSplitGenS7 = 
    do
        prng <- getGenS
        return (tplPrngSplit7 prng)
 
tplSplitGenS8 :: S.State Rnd.StdGen (Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen)
tplSplitGenS8 = 
    do
        prng <- getGenS
        return (tplPrngSplit8 prng)
 
tplSplitGenS9 :: S.State Rnd.StdGen (Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen)
tplSplitGenS9 = 
    do
        prng <- getGenS
        return (tplPrngSplit9 prng)
 
lPrngSplit :: Rnd.StdGen -> Integer -> [Rnd.StdGen]
lPrngSplit prng0 nCount
    | nCount > 0 = 
        let
            (prng1, prng2) = Rnd.split prng0
        in
            prng2 : (lPrngSplit prng1 (nCount - 1))
    | otherwise = []
 
splitPrng :: Rnd.StdGen -> (Rnd.StdGen)
splitPrng prng0 = 
        let
            [prng1] = lPrngSplit prng0 1
        in
            (prng1)
 
tplPrngSplit2 :: Rnd.StdGen -> (Rnd.StdGen, Rnd.StdGen)
tplPrngSplit2 prng0 = 
        let
            [prng1, prng2] = lPrngSplit prng0 2
        in
            (prng1, prng2)
 
tplPrngSplit3 :: Rnd.StdGen -> (Rnd.StdGen, Rnd.StdGen, Rnd.StdGen)
tplPrngSplit3 prng0 = 
        let
            [prng1, prng2, prng3] = lPrngSplit prng0 3
        in
            (prng1, prng2, prng3)
 
tplPrngSplit4 :: Rnd.StdGen -> (Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen)
tplPrngSplit4 prng0 = 
        let
            [prng1, prng2, prng3, prng4] = lPrngSplit prng0 4
        in
            (prng1, prng2, prng3, prng4)
 
tplPrngSplit5 :: Rnd.StdGen -> (Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen)
tplPrngSplit5 prng0 = 
        let
            [prng1, prng2, prng3, prng4, prng5] = lPrngSplit prng0 5
        in
            (prng1, prng2, prng3, prng4, prng5)
 
tplPrngSplit6 :: Rnd.StdGen -> (Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen)
tplPrngSplit6 prng0 = 
        let
            [prng1, prng2, prng3, prng4, prng5, prng6] = lPrngSplit prng0 6
        in
            (prng1, prng2, prng3, prng4, prng5, prng6)
 
tplPrngSplit7 :: Rnd.StdGen -> (Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen)
tplPrngSplit7 prng0 = 
        let
            [prng1, prng2, prng3, prng4, prng5, prng6, prng7] = lPrngSplit prng0 7
        in
            (prng1, prng2, prng3, prng4, prng5, prng6, prng7)
 
tplPrngSplit8 :: Rnd.StdGen -> (Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen)
tplPrngSplit8 prng0 = 
        let
            [prng1, prng2, prng3, prng4, prng5, prng6, prng7, prng8] = lPrngSplit prng0 8
        in
            (prng1, prng2, prng3, prng4, prng5, prng6, prng7, prng8)
 
tplPrngSplit9 :: Rnd.StdGen -> (Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen, Rnd.StdGen)
tplPrngSplit9 prng0 = 
        let
            [prng1, prng2, prng3, prng4, prng5, prng6, prng7, prng8, prng9] = lPrngSplit prng0 9
        in
            (prng1, prng2, prng3, prng4, prng5, prng6, prng7, prng8, prng9)

executes, with output like:

(MyData 1660924500 2147483396 0.8006679893360256 0.8162396936991755 (MyData2 0.6866312537716532 0.8180534811198655),MyData 1660964514 2147402014 0.8440472352553701 0.8162396936991755 (MyData2 0.6866312537716532 0.8180534811198655),MyData2 0.45086862247497494 0.36537830686886874,ScaleA 1.7497456354343925)
(MyData 1660924500 2147483396 0.8006679893360256 0.8162396936991755 (MyData2 0.6866312537716532 0.8180534811198655),MyData 1660964514 2147402014 0.8440472352553701 0.8162396936991755 (MyData2 0.6866312537716532 0.8180534811198655),MyData2 0.45086862247497494 0.36537830686886874,ScaleA 1.7497456354343925)

You could leave a comment if you were logged in.