Separated `Map` and `Filter`

* there is no reason to keep them in the same header

1 files changed, 34 insertions, 0 deletions

diff --git a/src/list/operation/higher/filter.h b/src/list/operation/higher/filter.h
new file mode 100644
index 0000000..8788aed
--- /dev/null
+++ b/src/list/operation/higher/filter.h
@@ -0,0 +1,34 @@
+#ifndef TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_FILTER_H_
+#define TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_FILTER_H_
+
+#include "fold.h"
+#include "conditional/if.h"
+
+namespace tav {
+
+template <
+	template<typename> class Function,
+	typename                 List
+>
+class Filter {
+	private:
+		template <
+			typename Current,
+			typename Previous
+		>
+		struct function_wrapper {
+			typedef If<
+				Function<Current>::type::value,
+				Cons<Current, Previous>,
+				Previous
+			> type;
+		};
+
+	public:
+		typedef typename Fold<function_wrapper, void, List>::type type;
+
+};
+
+}
+
+#endif  // TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_FILTER_H_