[jeremyjh]

The Haskell community wrestled with this for many years - may still I haven't really kept up. Last I was involved the most successful thing going on was Stackage where they encouraged no defensive upper bounds and ran continous builds on a large chunk of the most active parts of the ecosystem with every release to find actual compatibility issues, with automation to handle notifications back to owners and clear timelines if you wanted to stay in the next "LTS" release.

Things now seem to be stable enough that you just need the Cabal solver - but I suspect the broad nightly builds and visible failures/blockages probably help keep the ecosystem solvable.