Revamped partial function application

* moved internals into separate header i.e. the `detail` namespace relating to `Apply`
* implemented automatic alias selection by implementing aliae of the basic variadic `type` template alias in different base classes
** variadic partial application is implemented in `detail::apply_variadic`
*** `detail::apply_single` and `detail::apply_pair` define aliae to `detail::apply_variadic`'s `type` template alias
*** both restricted aliae derive from `detail::apply_variadic`
** `Apply` derives from any of the aliae defining base classes depending on the count of placeholders as determined by `detail::count_placeholders`
*** `Apply` is guaranteed to always be derived from `detail::apply_variadic` one way or the other
* changed functions, test cases and examples depending on `Apply` accordingly
** `Length` had to be reimplemented without `Apply` as it doesn't allow usage of aliae expecting a different count of arguments anymore
*** this is a advantage in the sense that core functionality of _TypeAsValue_ now doesn't depend on this complex partial application implementation anymore
*** such functionality may be reimplemented separately from `Apply`
* removed unnecessary `tav` namespace prefixes

4 files changed, 17 insertions, 10 deletions

diff --git a/src/list/operation/basic.h b/src/list/operation/basic.h
index cbbe22c..b4aa35a 100644
--- a/src/list/operation/basic.h
+++ b/src/list/operation/basic.h
@@ -2,17 +2,24 @@
 #define TYPEASVALUE_SRC_LIST_OPERATION_BASIC_H_
 
 #include "higher/fold.h"
-#include "function/apply.h"
 #include "operation/math.h"
 
 namespace tav {
 
-template <typename Pair>
-using Length = Fold<
-	Apply<Add, Size<1>, _1>::pair_type,
-	Size<0>,
-	Pair
->;
+template <typename Cons>
+class Length {
+	private:
+		template <typename, typename Accumulated>
+		using accumulate = Add<Size<1>, Accumulated>;
+
+	public:
+		typedef typename Fold<
+			accumulate,
+			Size<0>,
+			Cons
+		>::type type;
+
+};
 
 }
 
diff --git a/src/list/operation/contains.h b/src/list/operation/contains.h
index 51d7d9f..458acc0 100644
--- a/src/list/operation/contains.h
+++ b/src/list/operation/contains.h
@@ -12,7 +12,7 @@ template <
 	typename List
 >
 using Contains = Any<
-	Apply<EqualValue, tav::_0, Element>::template single_type,
+	Apply<EqualValue, _0, Element>::template type,
 	List
 >;
 
diff --git a/src/list/operation/delete.h b/src/list/operation/delete.h
index 2ff674c..a524667 100644
--- a/src/list/operation/delete.h
+++ b/src/list/operation/delete.h
@@ -12,7 +12,7 @@ template <
 	typename List
 >
 using Delete = Remove<
-	Apply<EqualValue, tav::_0, Element>::template single_type,
+	Apply<EqualValue, _0, Element>::template type,
 	List
 >;
 
diff --git a/src/list/operation/higher/sort.h b/src/list/operation/higher/sort.h
index f9146d6..5bc30c6 100644
--- a/src/list/operation/higher/sort.h
+++ b/src/list/operation/higher/sort.h
@@ -18,7 +18,7 @@ class Sort {
 		using pivot = typename Nth<index, Sequence>::type;
 
 		using partitions = typename Partition<
-			Apply<Comparator, pivot, tav::_0>::template single_type,
+			Apply<Comparator, pivot, _0>::template type,
 			typename DeleteNth<index, Sequence>::type
 		>::type;