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`

2 files changed, 13 insertions, 8 deletions

diff --git a/src/list/operation/concatenate.h b/src/list/operation/concatenate.h
index a5cbaa6..cf680c1 100644
--- a/src/list/operation/concatenate.h
+++ b/src/list/operation/concatenate.h
@@ -2,16 +2,23 @@
 #define TYPEASVALUE_SRC_LIST_OPERATION_CONCATENATE_H_
 
 #include "append.h"
-#include "higher/remove.h"
 #include "higher/fold.h"
+#include "conditional/if.h"
 
 namespace tav {
 
-template <typename ListOfLists>
+template <
+	typename    Head,
+	typename... Tail
+>
 using Concatenate = Fold<
 	Append,
 	void,
-	ListOfLists
+	If<
+		Boolean<sizeof...(Tail) == 0>,
+		Head,
+		List<Head, Tail...>
+	>
 >;
 
 }
diff --git a/src/list/operation/higher/sort.h b/src/list/operation/higher/sort.h
index 925ab89..51317fa 100644
--- a/src/list/operation/higher/sort.h
+++ b/src/list/operation/higher/sort.h
@@ -29,11 +29,9 @@ class quick_sort {
 
 	public:
 		using type = Concatenate<
-			List<
-				Eval<quick_sort<Comparator, lhs>>,
-				List<pivot>,
-				Eval<quick_sort<Comparator, rhs>>
-			>
+			Eval<quick_sort<Comparator, lhs>>,
+			List<pivot>,
+			Eval<quick_sort<Comparator, rhs>>
 		>;
 };