[Haskell-beginners] Re: Debugging overlapping instances (mtl vs transformers)

Paolo Losi paolo.losi at gmail.com
Thu Sep 9 04:47:39 EDT 2010

On 09/09/2010 10:35, Paolo Losi wrote:

> Overlapping instances for Monad (Either String)
> arising from a use of `tstampToForecasts'
> at ThreeLab/Gfs.hs:94:32-55
> Matching instances:
> instance (Control.Monad.Trans.Error.Error e) => Monad (Either e)
> -- Defined in Control.Monad.Trans.Error
> instance Monad (Either e)
> -- Defined in mtl-

Forgot to say... that's the error I get using cabal build

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