[Haskell-cafe] Re: Nested Monads Questions

2006-08-12 Thread Dan Doel
On 8/11/06, Dan Doel [EMAIL PROTECTED] wrote: The difference is in what the parameters to the classes MonadTrans and MonadIO represent. MonadIO m means that m is a monad into which IO-actions can be lifted. MonadTrans t means that (t m) is a monad into which m-actions can be lifted. However,

[Haskell-cafe] Re: Nested Monads Questions

2006-08-12 Thread Dan Doel
On 8/12/06, Dan Doel [EMAIL PROTECTED] wrote: Viola. Egads! In my haste, I failed to note that my mapping from the type synonym to the data constructor only works for a single nested transformer. lift will build arbitrarily nested CombinatorTs, but I'm not sure how to extract them into the

[Haskell-cafe] Re: Nested Monads Questions

2006-08-11 Thread Dan Doel
On 8/11/06, Stefan Aeschbacher [EMAIL PROTECTED] wrote: I'm trying to understand Monad Transformers. The code below works as expected but I have the following questions: I'll take a shot. - why can I use liftIO but not lift in the doSomething function? I fooled around a bit, and the answer