polysemy-RandomFu

Summary

• Polysemy effect and intepreters to use the random-fu library in a polysemy effect union (like an mtl stack).
• Includes an MTL "absorber" (see https://github.com/isovector/polysemy-zoo/blob/master/src/Polysemy/MTL.hs) for to random-fu MonadRandom typeclass.

Example (from the tests)

import           Polysemy
import           Polysemy.RandomFu

import qualified Data.Random                   as R
import qualified Data.Random.Source.PureMT     as R

getRandomInts :: Member RandomFu r => Int -> Sem r [Int]
getRandomInts nDraws =
  sampleRVar $ M.replicateM nDraws (R.uniform 0 (100 :: Int))
  
main :: IO ()
main = do
  seed <- R.newPureMT
  putStrLn . show $ runM . runRandomIOPureMT (R.pureMT seed) $ getRandomInts 5

should print a list of 5 pseudo-random integers. They will be different each time you run because the newPureMT function returns a different seed each time it's called. If you replace that seed in the R.pureMT argument to runRandomIOPureMT with a fixed number then you will get the same pseudo-random sequences each time. This can be useful for testing.

Notes

• See the tests (in https://github.com/adamConnerSax/Polysemy-Extra/blob/master/polysemy-RandomFu/test/RandomFuSpec.hs) for more details about how to use this effect