[runeks]

Stack enables application development in Haskell, as opposed to just library development. A proper library doesn't have more than 20-ish dependencies, in my opinion, and manually handling these and their version bounds is not a problem.

But when writing applications with hundreds of dependencies, manually figuring out a mutually compatible dependency range for all packages just isn't an option. At least not if you want to spend time prototyping code, rather than think about dependency ranges.

hpack solves additional problems with the .cabal format (sane defaults as opposed to build failure), and I highly recommend it, for application development at least. I just discovered it a month ago and now I wouldn't be able to live without it.