recompilation / overlapping instances

Christian Maeder maeder at
Mon May 29 05:40:13 EDT 2006

Hallo Thomas,

when compiling your sources in our context I get an "Overlapping 
instances" error (below).

However, first compiling the offending file (base/TI/OrigTiMonad.hs) and 
then compiling the rest works (but I don't want adapt our Makefile for 
this to do).

Could you adjust your sources? We're using ghc-6.4.2. Or is there a 
further compiler switch that would get this right?

I don't know if both instances are identical.

Cheers Christian

     Overlapping instances for Functor (Either (Error (HsIdentI i)))
       arising from use of `fmap' at 
     Matching instances:
       Imported from Control.Monad.Error: instance Functor (Either e)
         instance Functor (Either x)
     In a lambda abstraction: \ env ids -> fmap (fmap f) (m env ids)
     In the second argument of `($)', namely `\ env ids -> fmap (fmap f) 
(m env i
     In the definition of `fmap': fmap f (IM m) = IM $ (\ env ids -> ...)

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