I just noticed that the default directory layout that cabal uses (under .cabal) has changed between 1.16 and 1.18. In particular: In 1.16 -- libsubdir: $pkgid/$compiler -- datasubdir: $pkgid -- docdir: $datadir/doc/$pkgid in 1.18 -- libsubdir: $arch-$os-$compiler/$pkgid -- datasubdir: $arch-$os-$compiler/$pkgid -- docdir: $datadir/doc/$arch-$os-$compiler/$pkgid This is a rather big change: When the same package is built with multiple compilers, before they were stored all under the same dir, now the packages are grouped by compiler. This change is actually better from a system-installer (and uninstaller) point of view, and the Mac platfrom has been shipping with a customer cabal wrapper that sets up the user's default in a similar fashion for years. This change breaks the existing uninstaller, and will require some retrenching on the platform... I'm going to try to reconcile the existing "Mac way" with the "new way" since they are closer. - Mark