Maybe this is a beginners question... But here my problems description:
import Random import Control.Monad import qualified Control.Monad.State as S import Test.QuickCheck.Gen import Test.QuickCheck.Arbitrary
Each thing can have one of three types:
data Ontology = Thing1 Bool | ThingK Bool deriving (Show, Eq)
instance Arbitrary Ontology where arbitrary = oneof [ return $ Thing1 True , return $ ThingK True , return $ Thing1 False , return $ ThingK False ]
Liked to have a state monad runner for my arbitrary things as in "Real World Haskell", "Chapter 14. Monads" ("Random values in the state monad"). [RWH]:
-- file: ch14/Random.hs type RandomState a = S.State StdGen a
[RWH]: < -- file: ch14/Random.hs < getRandom :: Random a => RandomState a < getRandom = < S.get >>= \gen -> < let (val, gen') = random gen in < S.put gen' >> < return val [RWH]: < -- file: ch14/Random.hs < getTwoRandoms :: Random a => RandomState (a, a) < getTwoRandoms = liftM2 (,) getRandom getRandom [RWH]: < -- file: ch14/Random.hs < runTwoRandoms :: IO (Int, Int) < runTwoRandoms = do < oldState <- getStdGen < let (result, newState) = S.runState getTwoRandoms oldState < setStdGen newState < return result Thought getRandom function would be the best place to inject my unGen function call, but cannot get it to type-check:
getRandom :: Random a => RandomState [a] getRandom = S.get >>= \gen -> let (val, gen') = liftM2 (,) (unGen arbitrary gen 12) (random gen) in S.put gen' >> return val
A function not almost fulfilling my needs but the Random Number Generator isn't updated... I liked to have different [Ontology] occasions per call:
genArray :: [Ontology] genArray = unGen arbitrary (mkStdGen 42) 12 :: [Ontology]
Does anyone have the patience to help me out at least one step further? Cheers Daniel