importing (<=) from GHC.TypeLits

I want to import Nat and type-level (<=) from GHC.TypeLits: import GHC.TypeLits (Nat, (<=)) "Nat" is found this way, but (<=) is not: Module ‘GHC.TypeLits’ does not export ‘(<=)’ What is the trick? The doc only shows the anonymous import: http://www.haskell.org/ghc/docs/7.8.1-rc2/html/users_guide/promotion.html