[michaelt_]

This totally rewrites history. The idea of scrapping upper bounds was introduced by Brian O'Sullivan https://mail.haskell.org/pipermail/haskell-cafe/2012-August/... whereupon it was adopted by yesod as you can see by comparing http://hackage.haskell.org/package/yesod-1.1.0 (before bos's verdict) and http://hackage.haskell.org/package/yesod-1.1.0.1 (after bos's verdict). If you study the cabal file for yesod 1.1.0 you will see that the method it employed then was extreme restriction of constraints. I don't use stack all that much, and certainly disapprove of omitting upper bounds, but the truth is, it was a chamber of horrors to get really large complex builds to work in those days. pandoc and yesod in particular were really hopeless, and one was constantly explaining to beginners how to get these things to work. Now these problems don't arise; if you are building something that will require 50 libraries to be installed, of course you use stack.