[Haskell-cafe] Control.Exceptions and MonadIO

[oleg at pobox.com]

Robert Dockins wrote:
> One additional (very unfortunate) point is that higher-order IO monad
> combinators will not work on your monad, eg, the ones in
> Control.Exception.

Although that is true in general, for many useful and interesting
cases (including ReaderT, the state transformer, and the newtype wrapping
of IO) one _can_ use catch, bracket etc. constructs in MonadIO. Please
see this message and the follow-up discussion:

	http://www.haskell.org/pipermail/haskell/2006-February/017547.html