etad_rhs :: Type -- return a TyCon without pulling on rhs_ty
-- See Note [Tricky iface loop] in LoadIface
(etad_tvs, etad_rhs) = eta_reduce (reverse tvs) rhs_ty
-
+
eta_reduce :: [TyVar] -- Reversed
-> Type -- Rhs type
-> ([TyVar], Type) -- Eta-reduced version (tyvars in normal order)