mtl library in HEAD?

[Malcolm Wallace]

> The library installs fine with earlier versions of Haskell.  Is  
> there something wrong with my installation, or is this a new  
> incompatibility?  If the latter, is a corrected version of the mtl  
> library going to be available soon?  Alternatively, how can I fix it?

Yes, this is a new incompatibility.  The instance in question recently  
moved from the mtl package to the base package, after discussion on  
this list.

Until the next release of ghc/base/mtl, it will be necessary to use  
the HEAD versions of all of them (not merely the HEAD of ghc).

Regards,
     Malcolm