import Data.IntMap
import System.IO.Unsafe (unsafePerformIO)

main :: IO ()
main = do
   print $ step st

data State = State { im :: IntMap Int } deriving Show

st = State $ fromList [(0,0),(1,0),(2,0),(3,0),(7,0),(9,0)]

step :: State -> State
step st = st { im = mapWithKey (sim st m) (im st) }
   where
   m :: Int -> Maybe Int
   m n = unsafePerformIO $ do
      putStrLn $ unwords ["m",show n]
      pure $ im st !? n

sim :: State -> (Int -> Maybe Int) -> Key -> Int -> Int
sim st m k n = maybe (-1) id $ m (konst 1 n)

konst :: a -> b -> a
konst = const
{-# NOINLINE konst #-}