From 6291f3ce10aa8ebffa895f21c4ccb91b7349c66a Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Fri, 30 Jan 2015 19:31:30 +0100
Subject: Implemented `Remove` and `Partition` higher order list functions *
 `Remove` is a basic `Filter` alias that negates its predicate * `Partition`
 builds on both `Remove` and `Filter` to return both the elements satisfying a
 predicate and those which don't

---
 src/list/operation/higher/filter.h    | 22 ++++++++++++++++++----
 src/list/operation/higher/map.h       |  1 -
 src/list/operation/higher/partition.h | 21 +++++++++++++++++++++
 test.cc                               | 30 ++++++++++++++++++++++++++++++
 4 files changed, 69 insertions(+), 5 deletions(-)
 create mode 100644 src/list/operation/higher/partition.h

diff --git a/src/list/operation/higher/filter.h b/src/list/operation/higher/filter.h
index 8788aed..d91735e 100644
--- a/src/list/operation/higher/filter.h
+++ b/src/list/operation/higher/filter.h
@@ -7,7 +7,7 @@
 namespace tav {
 
 template <
-	template<typename> class Function,
+	template<typename> class Predicate,
 	typename                 List
 >
 class Filter {
@@ -16,16 +16,30 @@ class Filter {
 			typename Current,
 			typename Previous
 		>
-		struct function_wrapper {
+		struct predicate_wrapper {
 			typedef If<
-				Function<Current>::type::value,
+				Predicate<Current>::type::value,
 				Cons<Current, Previous>,
 				Previous
 			> type;
 		};
 
 	public:
-		typedef typename Fold<function_wrapper, void, List>::type type;
+		typedef typename Fold<predicate_wrapper, void, List>::type type;
+
+};
+
+template <
+	template<typename> class Predicate,
+	typename                 List
+>
+class Remove {
+	private:
+		template <typename Element>
+		using predicate_negator = Not<Predicate<Element>>;
+
+	public:
+		typedef typename Filter<predicate_negator, List>::type type;
 
 };
 
diff --git a/src/list/operation/higher/map.h b/src/list/operation/higher/map.h
index 1c577ca..a451b2a 100644
--- a/src/list/operation/higher/map.h
+++ b/src/list/operation/higher/map.h
@@ -2,7 +2,6 @@
 #define TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_MAP_H_
 
 #include "fold.h"
-#include "conditional/if.h"
 
 namespace tav {
 
diff --git a/src/list/operation/higher/partition.h b/src/list/operation/higher/partition.h
new file mode 100644
index 0000000..e42b971
--- /dev/null
+++ b/src/list/operation/higher/partition.h
@@ -0,0 +1,21 @@
+#ifndef TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_PARTITION_H_
+#define TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_PARTITION_H_
+
+#include "filter.h"
+
+namespace tav {
+
+template <
+	template<typename> class Predicate,
+	typename                 List
+>
+struct Partition {
+	typedef Cons<
+		typename Filter<Predicate, List>::type,
+		typename Remove<Predicate, List>::type
+	> type;
+};
+
+}
+
+#endif  // TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_PARTITION_H_
diff --git a/test.cc b/test.cc
index e7817f0..9168038 100644
--- a/test.cc
+++ b/test.cc
@@ -9,6 +9,7 @@
 #include "list/operation/contains.h"
 #include "list/operation/higher/map.h"
 #include "list/operation/higher/filter.h"
+#include "list/operation/higher/partition.h"
 #include "list/operation/higher/query.h"
 #include "list/generator/iota.h"
 #include "list/generator/make_list.h"
@@ -427,6 +428,35 @@ static_assert(
 	"(filter odd? (list 1 2 3)) != (list 1 3)"
 );
 
+// list remove
+
+static_assert(
+	std::is_same<
+		tav::List<tav::Int<1>, tav::Int<3>>::type,
+		tav::Remove<
+			tav::Even,
+			tav::List<tav::Int<1>, tav::Int<2>, tav::Int<3>>::type
+		>::type
+	>::value,
+	"(remove even? (list 1 2 3)) != (list 1 3)"
+);
+
+// list partition
+
+static_assert(
+	std::is_same<
+		tav::Cons<
+			tav::List<tav::Int<1>, tav::Int<3>>::type,
+			tav::List<tav::Int<2>>::type
+		>,
+		tav::Partition<
+			tav::Odd,
+			tav::List<tav::Int<1>, tav::Int<2>, tav::Int<3>>::type
+		>::type
+	>::value,
+	"(partition odd? (list 1 2 3)) != [(list 1 3) (list 2)]"
+);
+
 // list reverse
 
 static_assert(
-- 
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