====== Random values ======

  * example
    * code, module Main:<code Haskell>
{-# OPTIONS_GHC -fno-warn-orphans #-}

import qualified Randomisable as Rnd

main :: IO ()
main = do
  prng0 <- Rnd.newStdGen
  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>
    * code, module Randomisable:<code Haskell>
{-# 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)
</code>
    * executes, with output like:<code>
(MyData 1547211741 2147483396 0.2483644234579585 0.9836217202419262 (MyData2 0.4909809627910673 0.8713231916723704),MyData 1547251755 2147402014 0.2483644234579585 0.9836217202419262 (MyData2 0.4909809627910673 0.8713231916723704),MyData2 0.6269406052566662 0.2513090689294605,ScaleA 0.11255263338660004)
</code>


===== ✎ =====
~~DISCUSSION~~