generating hello world LLVM function from Haskell

hello-world-llvm.hs

import Control.Monad
import Data.Word
import LLVM.Core
import LLVM.Util.File

-- prints out "hello world"
bldGreet :: CodeGenModule (Function (IO ()))
bldGreet = do
    puts <- newNamedFunction ExternalLinkage "puts" :: TFunction (Ptr Word8 -> IO Word32)
    func <- withStringNul "Hello, World!" $ \greetz ->
      createFunction ExternalLinkage $ do
        tmp <- getElementPtr greetz (0::Word32, (0::Word32, ()))
        void $ call puts tmp
        ret ()
    return func

main :: IO ()
main = writeCodeGenModule "hello.bc" (_main =<< bldGreet)
  where
    _main :: (Function (IO ())) -> CodeGenModule (Function (IO ()))
    _main func = createNamedFunction ExternalLinkage "main" $ do
      call func
      ret ()