Re: mtl library in HEAD?

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