From d86aac04e5225e705af0dd7749fdc1c0454088a8 Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Mon, 2 Feb 2015 18:58:36 +0100
Subject: Implemented `Delete` in terms of `Remove` * analogously to how
 `Contains` is implemented as a wrapper around `Any` * added appropriate test
 case and lessened restrictions on `Contains`'s comparator

---
 src/list/operation/contains.h |  5 ++---
 src/list/operation/delete.h   | 25 +++++++++++++++++++++++++
 test.cc                       | 25 +++++++++++++++++++++++++
 3 files changed, 52 insertions(+), 3 deletions(-)
 create mode 100644 src/list/operation/delete.h

diff --git a/src/list/operation/contains.h b/src/list/operation/contains.h
index 9e752ed..d3f95fa 100644
--- a/src/list/operation/contains.h
+++ b/src/list/operation/contains.h
@@ -1,6 +1,7 @@
 #ifndef TYPEASVALUE_SRC_LIST_OPERATION_CONTAINS_H_
 #define TYPEASVALUE_SRC_LIST_OPERATION_CONTAINS_H_
 
+#include "type.h"
 #include "higher/query.h"
 
 namespace tav {
@@ -12,9 +13,7 @@ template <
 class Contains {
 	private:
 		template <typename Current>
-		struct comparator {
-			typedef std::is_same<Current, Element> type;
-		};
+		using comparator = EqualValue<Current, Element>;
 
 	public:
 		typedef typename Any<comparator, List>::type type;
diff --git a/src/list/operation/delete.h b/src/list/operation/delete.h
new file mode 100644
index 0000000..ad0a4cf
--- /dev/null
+++ b/src/list/operation/delete.h
@@ -0,0 +1,25 @@
+#ifndef TYPEASVALUE_SRC_LIST_OPERATION_DELETE_H_
+#define TYPEASVALUE_SRC_LIST_OPERATION_DELETE_H_
+
+#include "type.h"
+#include "higher/filter.h"
+
+namespace tav {
+
+template <
+	typename Element,
+	typename List
+>
+class Delete {
+	private:
+		template <typename Current>
+		using comparator = EqualValue<Current, Element>;
+
+	public:
+		typedef typename Remove<comparator, List>::type type;
+
+};
+
+}
+
+#endif  // TYPEASVALUE_SRC_LIST_OPERATION_DELETE_H_
diff --git a/test.cc b/test.cc
index fa082ea..da3193f 100644
--- a/test.cc
+++ b/test.cc
@@ -17,6 +17,7 @@
 #include "list/generator/iota.h"
 #include "list/generator/make_list.h"
 #include "list/generator/higher/list_tabulate.h"
+#include "list/operation/delete.h"
 
 #include "function/apply.h"
 
@@ -434,6 +435,30 @@ static_assert(
 	"(remove even? (list 1 2 3)) != (list 1 3)"
 );
 
+// list delete
+
+static_assert(
+	std::is_same<
+		tav::List<tav::Int<1>, tav::Int<3>>::type,
+		tav::Delete<
+			tav::Int<2>,
+			tav::List<tav::Int<1>, tav::Int<2>, tav::Int<3>>::type
+		>::type
+	>::value,
+	"(delete 2 (list 1 2 3)) != (list 1 3)"
+);
+
+static_assert(
+	std::is_same<
+		tav::List<tav::Int<1>, tav::Int<2>, tav::Int<3>>::type,
+		tav::Delete<
+			tav::Int<4>,
+			tav::List<tav::Int<1>, tav::Int<2>, tav::Int<3>>::type
+		>::type
+	>::value,
+	"(delete 4 (list 1 2 3)) != (list 1 2 3)"
+);
+
 // list partition
 
 static_assert(
-- 
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