[Haskell-cafe] what is wrong w my IORef Word32 ?

[Joerg Fritsch]

All, what is wrong w the below code?

I get an type error related to the operation shiftL

import Data.Bits
import Data.Word
import Data.IORef

data Word32s = Word32s { x :: IORef Word32 }

bitfield :: Word32
bitfield = 0

mkbitfield :: Word32 -> IO Word32s
mkbitfield i = do the_bf <- newIORef i
                  return (Word32s the_bf)

sLbitfield :: Integer -> Word32s -> IO ()
sLbitfield i (Word32s bf) = do modifyIORef bf (shiftL i)

main::IO()
main = do
     oper_bf <- mkbitfield bitfield 
     sLbitfield 2 oper_bf



bf_003.hs:15:48:
    Couldn't match type `Int' with `Word32'
    Expected type: Word32 -> Word32
      Actual type: Int -> Word32
    In the return type of a call of `shiftL'
    In the second argument of `modifyIORef', namely `(shiftL i)'
    In a stmt of a 'do' block: modifyIORef bf (shiftL i)

bf_003.hs:15:55:
    Couldn't match expected type `Word32' with actual type `Integer'
    In the first argument of `shiftL', namely `i'
    In the second argument of `modifyIORef', namely `(shiftL i)'
    In a stmt of a 'do' block: modifyIORef bf (shiftL i)



Thanks,
--Joerg