In the case of the Haskell ecosystem, I think that achieving this golden rule is hard specifically because not every package conforms to semantic versioning.
For example, the newly released `mtl`, which is a dependency of many other packages, breaks backwards compatibility from version 2.2 to 2.3. Personally, I'd expect to be able to have a dependency requirement like `mtl = 2.*` and forget about it forever.
If package versions were 'updated' to follow semantic versioning (e.g. `mtl` is not implicitly a version 3), we might have a better view of the current level of coherence of the Haskell ecosystem.
For example, the newly released `mtl`, which is a dependency of many other packages, breaks backwards compatibility from version 2.2 to 2.3. Personally, I'd expect to be able to have a dependency requirement like `mtl = 2.*` and forget about it forever.
If package versions were 'updated' to follow semantic versioning (e.g. `mtl` is not implicitly a version 3), we might have a better view of the current level of coherence of the Haskell ecosystem.