[Haskell-cafe] Either instance of Monad?

[Daniel Fischer]

On Wednesday 23 February 2011 14:14:46, Yves Parès wrote:
> The latest, I think :
> GHC 7.0.1,
> mtl-2.0.1.0,
> base-4.3.0.0

Hmm, that's exactly what I have. Weirder and weirder.
For the moment, I'm out of ideas.