Can someone provide "for-dummies" example of how to use `MonadRandom'?
Currently I have code that does stuff like passing around the generator variable, all the way from the main function:
main = do
g <- getStdGen
r <- myFunc g
putStrLn "Result is : " ++ show r
--my complicated func
myFunc g x y z = afunc g x y z
afunc g x y z = bfunc g x y
bfunc g x y = cfunc g x
cfunc g x = ret where
(ret, _ ) = randomR (0.0, 1.0) g
Thanks
Basically all the extra g
parameters can just be dropped. You then get random numbers using the functions from Control.Monad.Random (such as getRandomR
). Here is your example (I added some args to make it compile):
import Control.Monad.Random
main = do
g <- getStdGen
let r = evalRand (myFunc 1 2 3) g :: Double
-- or use runRand if you want to do more random stuff:
-- let (r,g') = runRand (myFunc 1 2 3) g :: (Double,StdGen)
putStrLn $ "Result is : " ++ show r
--my complicated func
myFunc x y z = afunc x y z
afunc x y z = bfunc x y
bfunc x y = cfunc x
cfunc x = do
ret <- getRandomR (0.0,1.0)
return ret
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