Date: Tue, 17 Nov 2009 11:59:56 +0100 (CET) From: Henning Thielemann

On Tue, 17 Nov 2009, Valery V. Vorotyntsev wrote:

...

Thus, the question is: are there any transformers-specific features iteratee package needs, or can it just go with mtl?

The question is, whether Iteratee needs functions of MTL that transformers does not provide? 'Transformers' is the more basic package, entirely Haskell 98, thus should be prefered. It is however sad, that Transformers cannot easily be used with GHCi in parallel with MTL installed. I was always against that ... Renaming Control.Monad.Trans and Control.Monad.Identity to something else would solve the conflict. I'm also not happy, that you have to choose between monads-fd and monads-tf. I think it would be better to be able to have both type class approaches.

Iteratee does not need any MTL functions that transformers does not provide. It does the following: 1) implement instances of MonadTrans and MonadIO 2) uses lift and liftIO (polymorphically) There's no technical reason iteratee couldn't use mtl, and as Erik mentions, if you change the dependency it works just fine. For myself, I can be swayed by user demand, although I'd like to see the outcome of this discussion before committing to any changes. In all honesty, I never thought iteratee would generate enough interest for this to matter. It's not a particularly popular package. Cheers, John