By making dictionaries explicit we might be able to unify instantiate,
instantiateFull, reduce and normalise.

class HasKit a where
  applyKit :: Kit m -> a -> m a

data Kit m = Kit { termKit :: TermKit m
		 , typeKit :: TypeKit m
		 , listKit :: ListKit m
		 ...
		 }

type ListKit m = forall a. HasKit a => Kit -> [a] -> m [a]
data TermKit m = TermKit
  { varKit :: Nat -> Args -> m Term
  , lamKit :: Hiding -> Abs Term -> m Term
  ...
  }