Constrained Type Families?

GHC Devs, The wiki page for Phase I of Dependent Haskell describes an approach to constrained type families: https://ghc.haskell.org/trac/ghc/wiki/DependentHaskell/Phase1#Typefamilyequa... https://ghc.haskell.org/trac/ghc/wiki/DependentHaskell/Phase1#Typefamilyequa... Did that land in GHC 8.0 and, if so, is the updated syntax documented somewhere? V/r, -Evan