But that's only one half of the "package interoperability" issue. I face this first hand on a daily basis with my Stackage maintenance. I spend far more time reporting issues of restrictive upper bounds than I do with broken builds from upstream changes. So I look at this as purely a game of statistics: are you more likely to have code break because version 1.2 of text changes the type of the map function and you didn't have an upper bound, or because two dependencies of yours have *conflicting* versions bounds on a package like aeson[2]? In my experience, the latter occurs far more often than the former.