import Data.IORef
import Control.Monad

main = do
   i <- newIORef 0
   
   let loop = do
        iNow <- readIORef i
        when (iNow < 10) $ do
          print i
          modifyIORef i (+1)
          loop
   loop

But obviously, you should avoid this. mapM_ print [0..9] works much better.

import Data.IORef
import Control.Monad

main = do
   i <- newIORef 0
   
   let loop = do
        iNow <- readIORef i
        when (iNow < 10) $ do
          print i
          modifyIORef i (+1)
          loop
   loop

But obviously, you should avoid this. mapM_ print [0..9] works much better.

I see you have to i variables in there with different increment. Well, it's obvious how to add that here. You can stay to the manual recursion through loop. A little better is replacing one IORef by a simple forM_. Preferrably, try not to use any IORef at all but only functional structures.