Introducing Unit!

Summary: title

Test Plan: tests

Reviewed By: hannesr@fb.com

Subscribers: exa, folly-diffs@, jsedgwick, yfeldblum, chalfant

FB internal diff: D2022859

Signature: t1:2022859:1429920863:0d3afce9779a790baf246de97f98812e23e1574d

folly/futures/Try.h

@@ -24,6 +24,7 @@
 #include <folly/Memory.h>
 #include <folly/futures/Deprecated.h>
 #include <folly/futures/FutureException.h>
+#include <folly/futures/Unit.h>
 
 namespace folly {
 

folly/futures/Unit.h

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2015 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#pragma once
+namespace folly {
+
+struct Unit {};
+
+}