It is the "batteries included" version of Haskell that comes with basically everything you need to write production ready software. There are obviously a lot of useful packages on `cabal`, but they are mostly useful so that you don't have to recreate the wheel (or want to do web-dev).
It's also meant to be used as a reference for distro package maintainers. If your code builds properly with the current platform, you can be confident it will build properly in most systems.
It is the "batteries included" version of Haskell that comes with basically everything you need to write production ready software. There are obviously a lot of useful packages on `cabal`, but they are mostly useful so that you don't have to recreate the wheel (or want to do web-dev).