[Haskell-cafe] category-extras clash with transformers

[Tony Morris]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

I have installed mtl-1.1.1.0 so that xmonad-contrib-0.9.1 would compile
with GHC 6.12.1.
http://permalink.gmane.org/gmane.comp.lang.haskell.xmonad/10603

Then I tried to installed category-extras-0.53.5, which clashed with
transformers-0.2.2.0 for the Applicative/Monad instances for Either.

Is there any way out of this problem? Thanks for any pointers.

$ ghc-pkg list | grep mtl
    mtl-1.1.1.0
    mtl-2.0.1.0
$ ghc-pkg list | grep transformers
    transformers-0.2.2.0
$ cabal install category-extras
...
[39 of 99] Compiling Control.Monad.Either ( src/Control/Monad/Either.hs,
dist/build/Control/Monad/Either.o )

src/Control/Monad/Either.hs:44:9:
    Duplicate instance declarations:
      instance Monad (Either e)
        -- Defined at src/Control/Monad/Either.hs:44:9-24
      instance Monad (Either e)
        -- Defined in transformers-0.2.2.0:Control.Monad.Trans.Error

src/Control/Monad/Either.hs:49:9:
    Duplicate instance declarations:
      instance Applicative (Either e)
        -- Defined at src/Control/Monad/Either.hs:49:9-30
      instance Applicative (Either e)
        -- Defined in transformers-0.2.2.0:Control.Monad.Trans.Error

src/Control/Monad/Either.hs:53:9:
    Duplicate instance declarations:
      instance MonadFix (Either e)
        -- Defined at src/Control/Monad/Either.hs:53:9-27
      instance MonadFix (Either e)
        -- Defined in transformers-0.2.2.0:Control.Monad.Trans.Error
cabal: Error: some packages failed to install:
category-extras-0.53.5 failed during the building phase. The exception
was:
ExitFailure 1

- -- 
Tony Morris
http://tmorris.net/

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.10 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/

iEYEARECAAYFAkznxgQACgkQmnpgrYe6r60dkACfZQkYKbMOQuGfaVpFb2MfhJWD
asAAn1/hoX+m/YpUOch3r4NsR99y2htz
=IsZc
-----END PGP SIGNATURE-----