[Yhc] Yhc using mtl

[Stefan O'Rear]

On Wed, Apr 11, 2007 at 11:50:03PM +0100, Neil Mitchell wrote:
> There are two parts of the mtl - one provides monads, one provides
> monad transformers. In general the monad half is Haskell 98, the
> transformer half is not - we've been careful to stick to the monad
> half so far. The mtl is actually being split soon into a Haskell 98
> half and a MPTC/FD half.

Actually, even the transformer half is Haskell 98 - it requires higher
kinds, but those have been with us since forever (Monad uses them).
The trouble spot is with the automatic lifting, so if we use enough
'lift's by hand, we can stay H98. 

Stefan