Making GHC upgrades easy

blamario: > > if impl(ghc >= 7.5) > other-extensions: PolyKinds > The issue being that this just enables or disables the extensions enabled instead of giving you version bounds. You could simulate this by giving impossible build dependencies for certain ghc versions: if impl(ghc <= 7.5) build-depends: base < 0 But this wouldn’t be a satisfactory solution since you then can’t use the cabal constraint solver here. You could add a dependency to the ghc or ghc-internal or ghc-experimental packages, but for most packages these are pointless dependencies, and this obviously wouldn’t work for alternative haskell compilers like mhs.