strange difference between old and hierachical module names

Hi,

I am trying to compile some modules with old imports
such "import MonadFix". These modules compile fine
with GHC 6.0 latest RPM, and also on CVS source tree
6.1 somewhere from july.

However, the file below does NOT get through with GHC HEAD.
I get ...

> Compiling Foo              ( Foo.hs, interpreted )
>  
> Foo.hs:13: `mfix' is not a (visible) method of class `MonadFix'
> Failed, modules loaded: none.

If I use the new "import Control.Monad.Fix" instead of MonadFix,
everything works fine. This is a bit strange because
for most old imports there is no such problem.
Seems to be something special going on with MonadFix.

Thanks,
Ralf



----------------------------------------------------------------

module Foo where

-- Does not work 6.3 as 2 Nov 2003
import MonadFix
-- Works with 6.3
-- import Control.Monad.Fix

data Foo a = Foo a

instance Monad Foo

instance MonadFix Foo where
        mfix = undefined