Enabled `Concatenate` to concatenate a variadic pack of lists

* analogously to arbitrary list count concatenation in Scheme's `append`
** implemented for `Concatenate` instead as it fits better with the structure between `Append` and `Concatenate`

1 files changed, 7 insertions, 5 deletions

diff --git a/src/conditional/cond.h b/src/conditional/cond.h
index ca5e46d..4def611 100644
--- a/src/conditional/cond.h
+++ b/src/conditional/cond.h
@@ -9,12 +9,14 @@ namespace tav {
 
 namespace detail {
 
-template <typename Pair>
-using cond_predicate = IsTrue<Car<Pair>>;
-
 template <typename... Branches>
-struct select_cond_branch {
-	using type = Eval<detail::find_variadic<detail::cond_predicate, Branches...>>;
+class select_cond_branch {
+	private:
+		template <typename Pair>
+		using predicate = IsTrue<Car<Pair>>;
+
+	public:
+		using type = Eval<detail::find_variadic<predicate, Branches...>>;
 
 	static_assert(
 		IsPair<type>::value,