[Haskell-cafe] Re: Foralls in records
adde at trialcode.com
Wed Mar 14 12:40:13 EDT 2007
Chris Kuklewicz <haskell <at> list.mightyreason.com> writes:
> Searching the haskell wiki for MonadIO gives several examples.
> > instance MonadIO m => MonadIO (ExitT e m) where
> > liftIO = lift . liftIO
> Where you can see you are just delegating the work of the transformer to the
> underlying monad. Eventually it hits the bottom of the stack and sees:
> > instance MonadIO IO where
> > liftIO = id
Ah, so to combine my monad with IO i need to write a monad Transformer
(TransactionT), then I can make it an instance of MonadIO?
I found examples like the ones you gave but the whole transformer-part got me
a bit confused. Sorry, should have spent some more time reading before asking.
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