On Tue, Oct 01, 2013 at 09:29:00AM +0200, Niklas Haas wrote: > On Tue, 1 Oct 2013 02:21:13 -0500, John Lato <jwl...@gmail.com> wrote: > > It's not a solution per se, but it seems to me that there's no need for the > > Monad superclass constraint on MonadIO. If that were removed, we could > > just have > > > > class LiftIO t where > > liftIO :: IO a -> t a > > > > and it would Just Work. > > One concern with this is that it's not exactly clear what the semantics > are on LiftIO (is liftIO a >> liftIO b equal to liftIO (a >> b) or not?) > and the interaction between LiftIO and Applicative/Monad would have to > be some sort of ugly ad-hoc law like we have with Bounded/Enum etc.
What is this 'ad-hoc law' you are talking about ? > > Furthermore, you might end up specifying a lot of ‘redundant’ > constraints like (Monad m, LiftIO m) that way, just a thing to keep in > mind. > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe -- Jose Antonio Lopes Ganeti Engineering Google Germany GmbH Dienerstr. 12, 80331, München Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg Geschäftsführer: Graham Law, Christine Elizabeth Flores Steuernummer: 48/725/00206 Umsatzsteueridentifikationsnummer: DE813741370 _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
