{-# LANGUAGE TemplateHaskell, RankNTypes, TypeOperators, TypeInType, GADTs #-} module T8031 where import Data.Proxy import Data.Kind data SList :: [k] -> * where SCons :: Proxy h -> Proxy t -> SList (h ': t) $( [d| foo :: forall (a :: k). Proxy a -> forall (b :: [k]). Proxy b -> SList (a ': b) foo a b = SCons a b |] )