spec_tys = [mk_spec_ty tv ty | (tv, Type ty) <- tyvars `zip` args]
dicts = [dict_expr | (_, dict_expr) <- theta `zip` (drop n_tyvars args)]
spec_tys = [mk_spec_ty tv ty | (tv, Type ty) <- tyvars `zip` args]
dicts = [dict_expr | (_, dict_expr) <- theta `zip` (drop n_tyvars args)]