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

1 files changed, 1 insertions, 1 deletions

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
 >;