On Sat, 3 Jan 2009, Henning Thielemann wrote:
I think I now have general Applicative functionality ...
I hope the following is a proper Monad implementation. In contrast to Applicative a Writer for sequencing actions does no longer work, instead I need a State monad. newtype LazyIO a = LazyIO {runLazyIO :: StateT RunAll IO a} data RunAll = RunAll deriving Show instance Monad LazyIO where return x = LazyIO $ return x x >>= f = LazyIO $ mapStateT unsafeInterleaveIO . runLazyIO . f =<< mapStateT unsafeInterleaveIO (runLazyIO x) instance MonadIO LazyIO where liftIO m = LazyIO $ StateT $ \RunAll -> fmap (\x->(x,RunAll)) m evalLazyIO :: LazyIO a -> IO a evalLazyIO = flip evalStateT RunAll . runLazyIO I'll write some tests and upload it to Hackage. Thank you for being a patient audience. ;-)