Re: [Haskell-cafe] How to determine correct dependency versions for a library?

The blacklisting approach has one major disadvantage that noone has mentioned yet: Adding more restrictive constraints does not work, the broken package will be on hackage forever, while adding a new version with relaxed constraints works well.

That illustrate real problem It's not possible to specify correct version constraints when package is uploaded. So one have to choose between optimistic and conservative approach. Both have disadvantages. In ideal world one need ability to adjust version bounds after package upload.