Just Haskell being better than Java at being Java

Java.hs

import Control.Monad
import Control.Monad.ST
import Data.STRef
import Data.Maybe

data Iterator s a =
  Iterator {
    next ::
      ST s (Maybe a)
  , hasNext :: 
      ST s Bool
  }

-- [1,3,5,7,9]
from1to9by2 ::
  Iterator s Int
from1to9by2 =
  let current = newSTRef (Just 1)
  in Iterator {
    next =
      do c <- current
         r <- readSTRef c
         modifySTRef c (>>= \n' -> if n' == 9 then Nothing else Just n')
         return r
  , hasNext = 
      do c <- current
         r <- readSTRef c
         return (isNothing r)
  }

while ::
  Monad m =>
  m Bool
  -> m a
  -> m ()
while p a =
  do q <- p
     when q (a >> while p a)

whileHasNext ::
  Iterator s a
  -> (a -> ST s a)
  -> ST s ()
whileHasNext i k =
  while
    (hasNext i)
    (next i >>= k . fromMaybe (error "lol: scru u, no correct programs 4 u."))