Revamped to use `Cons` as a function and `Pair` as its result

* this is analogous to _Scheme_ where a pair (dot-expression) is returned from a call to `cons`
* `Head` and `Tail` are kept as direct references to the `CAR` and `CDR` values of a pair to match e.g. the math operators

4 files changed, 11 insertions, 15 deletions

diff --git a/src/list/operation/higher/filter.h b/src/list/operation/higher/filter.h
index 3fc08ee..acc1422 100644
--- a/src/list/operation/higher/filter.h
+++ b/src/list/operation/higher/filter.h
@@ -18,7 +18,7 @@ class Filter {
 		>
 		using predicate_wrapper = If<
 			Predicate<Current>::type::value,
-			Cons<Current, Previous>,
+			typename Cons<Current, Previous>::type,
 			Previous
 		>;
 
diff --git a/src/list/operation/higher/map.h b/src/list/operation/higher/map.h
index a451b2a..9cb6524 100644
--- a/src/list/operation/higher/map.h
+++ b/src/list/operation/higher/map.h
@@ -15,12 +15,10 @@ class Map {
 			typename Current,
 			typename Previous
 		>
-		struct function_wrapper {
-			typedef Cons<
-				typename Function<Current>::type,
-				Previous
-			> type;
-		};
+		using function_wrapper = Cons<
+			typename Function<Current>::type,
+			Previous
+		>;
 
 	public:
 		typedef typename Fold<function_wrapper, void, List>::type type;
diff --git a/src/list/operation/higher/partition.h b/src/list/operation/higher/partition.h
index e42b971..a0ea379 100644
--- a/src/list/operation/higher/partition.h
+++ b/src/list/operation/higher/partition.h
@@ -9,12 +9,10 @@ template <
 	template<typename> class Predicate,
 	typename                 List
 >
-struct Partition {
-	typedef Cons<
-		typename Filter<Predicate, List>::type,
-		typename Remove<Predicate, List>::type
-	> type;
-};
+using Partition = Cons<
+	typename Filter<Predicate, List>::type,
+	typename Remove<Predicate, List>::type
+>;
 
 }
 
diff --git a/src/list/operation/higher/take_while.h b/src/list/operation/higher/take_while.h
index 27f58ed..d04dc2d 100644
--- a/src/list/operation/higher/take_while.h
+++ b/src/list/operation/higher/take_while.h
@@ -12,10 +12,10 @@ template <
 struct TakeWhile {
 	typedef typename If<
 		Predicate<Head<Current>>::type::value,
-		Cons<
+		typename Cons<
 			Head<Current>,
 			typename TakeWhile<Predicate, Tail<Current>>::type
-		>,
+		>::type,
 		void
 	>::type type;
 };