On 14/10/2010 12:01, Michael Snoyman wrote:
I have a recommendation of how to fix this: the MonadCatchIO typeclass should be extended to include finally, onException and everything else. We can provide default definitions which will work for most monads, and short-circuiting monads like ErrorT (and I imagine ContT as well) will need to override them.
Hi Michael, As an haskell newbie, I've got some questions on this matter. Is it using ErrorT instead of extensible exeptions really necessary? I've read your comment stating that we cannot pass function arguments to Exceptions because of the Show class constraint. But is that really limiting? Wouldn't your use case (e.g. HTTP redirection in Yesod) be implementable with extensible exceptions? I would guess that the rule of thumb would be not to mix extensible exception and ErrorT whenever it is possibile. I've quickly read your post on inverting transformer stacks and, from my newbie point of view, I feel that the extra complexity isn't worth the gain. Thanks Paolo My own rule of thumb would be not using _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
