Since I got some verification and encouragement from abieber@ and Evan Silberman, here's a full set of all the existing Haskell binary ports on top of our in-tree ghc version: https://github.com/blackgnezdo/ports/tree/cabal-ghc-8.6.4
I'm happy to send them in whatever way people like, though ideally I'd want to submit devel/happy and the framework before proceeding with more. Thanks Greg