different flavours of Monad Template Library

[ajb at spamcop.net]

G'day all.

Quoting Ross Paterson <ross at soi.city.ac.uk>:

> I agree.  I had a go at such a restructuring of mtl a while ago:
>
> 	http://darcs.haskell.org/packages/transformers/
> 	http://darcs.haskell.org/packages/mtl-split/

I'm curious if anyone has tried restructuring MTL with coproducts
rather than transformers.  Coproducts seem more "natural", if slightly
harder to write.

Cheers,
Andrew Bromage