On Fri, Oct 15, 2004 at 07:54:46PM -0700, [EMAIL PROTECTED] wrote: > > Andrew Pimlott wrote: > > I want values in my existential type to denote, for some monad, a > > monadic operation and a way to run the monad. Except, I want it mix > > the operation with operations in another monad, so it use a monad > > transformer. > > I'm afraid, that phrase was a little misleading. It seems that you > meant: > - encapsulate one _specific_ monad transformer > - to be able to apply it to _any_ (not some!) monad
Yes. I wrote that quickly (grammar mistakes too) and thought the code would make it clear. But it would have been better to make the words precise. > > data Bar a m = forall t. (MonadTrans t, Monad (t m)) => > > Bar (t m a -> m a) (t m Int) > > > > data Foo = Foo (forall a m. Monad m => Bar a m) Wow, very nice. Just do it in two steps! Thank you for this enlightening solution. Andrew _______________________________________________ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
