To find out who else uses your favorite functions and how: http://stuff.codereview.me/lts/9.2 . For example, click 'async' at http://stuff.codereview.me/lts/9.2/#async-2.1.1.1/Control/Concurrent/Async.hs?corpus&signature&line=175 to get all the callsites of that method. There are additional files available at http://stuff.codereview.me/ if you want to serve the xrefs locally, or merge your own packages into the index (assuming you use the same stackage lts version). A request: the crossreferencing is pretty usable, but far from complete. If you find any issues (missing crossreferences or bad ones), please have a look at the buglist at https://github.com/google/haskell-indexer/issues, and thumbs-up any that you find hurting, or open new ones! Thank you & happy code browsing, Robin