bracket, (un)block and MonadIO

[Simon Marlow]

=20
> On Friday 05 September 2003 1:02 pm, Keith Wansbrough wrote:
> > >  	-- ** The @handle@ functions
> > > -	handle,	   -- :: (Exception -> IO a) -> IO a -> IO a
> > > -	handleJust,-- :: (Exception -> Maybe b) -> (b -> IO a)=20
> -> IO a -> IO a
> > > +	handle,	   -- :: MonadIO m =3D> (Exception -> m a) -> m a -> m a
> > > +	handleJust,-- :: (Exception -> Maybe b) -> (b -> m a)=20
> -> m a -> m a
> >
> > Is the MonadIO constraint on m intentionally missing from=20
> handleJust?
>=20
> No, it's an unfortunate omission.  Thanks for pointing that out!
> Corrected patch attached.

This patch is still too deeply wired-in for my liking.  It generalises
the types of all the IO-related functions in Control.Exception.

We don't intend to generalise *every* IO function over MonadIO, that's
what liftIO is for.  And hence, we shouldn't also generalise functions
that take IO-typed arguments, since that is what liftIO' is for, and so
on.  By all means provide the generalised versions for convenience, but
I don't believe we should generalise the originals.

Cheers,
	Simon