For a very long time, I've used a local script to uninstall libraries. Initially it was very simple: use ghc-pkg field to find and remove library-dirs, import-dirs, and haddock-html, and call ghc-pkg unregister. It served well for a long time, but eventually I got tired of copy paste games and extended it to be able to recursively delete dependents too. Unfortunately now it's no longer so simple. The main problem is that the only way I know to find dependents is to ghc-pkg unregister, and see what the error message complains about. That's obviously pretty bad, since by that time you've already unregistered, so it's too late to back out. The non-atomic nature of unregister+rm has always caused problems anyway, since if unregister succeeds, but the remove fails, we are stuck with a partial install. Recursive delete is too error prone, so I reverted that. And then I discovered that hmatrix helpfully includes /opt/local/lib and /usr/local/lib in its library-dirs, so clearly just deleting whatever the package tells me is not very safe. All this has led me to believe uninstalling packages is not so simple, and maybe there should be an actual real way to do it, not everyone hacking up their own dangerous shell scripts. So... is there? Should there be one? Is there interest in one? How do other people uninstall libraries? Is there a better interface to the pkg db than ghc-pkg? Is there a better way to find dependents than ghc-pkg unregister?