Currently, Summoner supports scaffolding Haskell projects for GHC version 7.10.3 (which is the oldest supported version at the moment). Supporting this particular version has the following maintenance costs:

1. It's extremely difficult (and almost impossible) to test that scaffolded projects are built with GHC-7.10.3 automatically.
2. We continue to bring modern Haskell features for Summoner to provide best-practices. But old GHC versions may not support them. Without testing, such new features may break, and it's not a good UX to provide a non-working feature.
3. It's more code to maintain, test and worry about without noticeable benefits. Haskell libraries usually support the last three major GHC versions. And API gap between GHC 7.10 and 8.0 is generally too big for people to support GHC-7.10.3 in their libraries.
4. ghc-options in the .cabal file will become more concise and scaffolded projects will become even smaller without losing any features, since we don't need to maintain cabal conditionals.

I can imagine that we will continue dropping ancient GHC versions from Summoner In the future to keep the project alive, maintainable and remove bitrot. But so far, only GHC-7.10 causes some unpleasant experience.