Re: [Haskell-beginners] Builds with cabal, but not with GHC

On Wed, Sep 28, 2011 at 03:03:33PM +0000, Amy de Buitléir wrote:

Test.hs:20:9: No instance for (mtl-1.1.1.1:Control.Monad.Error.Class.MonadError CPError (ErrorT CPError IO))

I don't know a solution, but just want to point out that this error message smacks of inconsistent package versions being used. Something else used mtl-1.1.1.1 and the current module is being compiled with a different version of mtl, or something like that. Hopefully this can provide a fruitful direction of investigation... -Brent