Hi, alanasp has proposed a Deprecating Exports mechanism: https://github.com/alanasp/ghc-proposals/blob/patch-2/proposals/deprecating_... The gist is explained by this: module Data.List ( ... {-# DEPRECATE lines "Exported from Data.String instead" #-} , lines ...t ) where i.e. DEPRECATE pragmas in export lists cause warning when some other module uses the deprecated symbol when it is imported (only) via some deprecated export. This is a GSOC 2018 project, mentored by Matthew Pickering and Erik de Castro Lopo. The feature has a clear use-case, is self-contained and David Feuer (the containers maintainer) has already confirmed that there is a real demand for this. I suggest acceptance! As always, I will understand silence as tactic consensus. Cheers, Joachim -- Joachim Breitner mail@joachim-breitner.de http://www.joachim-breitner.de/