Update README and add an example

README.md

@@ -1 +1,47 @@
-# A utility library for using bitwise operators on flag enums
+# A C++20 library for using bitwise operators on flag enums
+
+This library provides a set of free function templates which perform bitwise opertions on scoped enums that satisfy the `Flag` concept. When these function templates are used, instead of return `int` like normal bitwise operators, they return the underlying type of the input enum.
+
+## Examples
+
+```cpp
+#include <cassert>
+#include <cstdint>
+#include <flag.hpp>
+
+enum class FilePermission : std::uint16_t {
+  all_execute = 0b0'000'000'001,
+  all_write   = 0b0'000'000'010,
+  all_read    = 0b0'000'000'100,
+
+  group_execute = 0b0'000'001'000,
+  group_write   = 0b0'000'010'000,
+  group_read    = 0b0'000'100'000,
+
+  user_execute = 0b0'001'000'000,
+  user_write   = 0b0'010'000'000,
+  user_read    = 0b0'100'000'000,
+
+  directory = 0b1'000'000'000
+};
+
+int main() {
+  using namespace river; // All operators are define in the river namespace
+
+  // type of file_permission is std::uint16_t
+  auto const file_permission = FilePermission::all_execute | FilePermission::all_write |
+                               FilePermission::all_read | FilePermission::group_execute |
+                               FilePermission::group_write | FilePermission::group_read |
+                               FilePermission::user_execute | FilePermission::user_write |
+                               FilePermission::user_read | FilePermission::directory;
+
+  auto const all_execute = has<FilePermission::all_execute>(file_permission);
+  auto const user_write  = has<FilePermission::user_write>(file_permission);
+
+  assert(all_execute);
+  assert(user_write);
+}
+```
+
+## Usage
+This is a header only library, copy the file `flag.hpp` to your source code and start using it.

examples/file_permission.cpp

@@ -22,8 +22,11 @@ int main() {
   using namespace river; // All operators are define in the river namespace
 
   // type of file_permission is std::uint16_t
-  auto const file_permission =
-      FilePermission::all_execute | FilePermission::all_read | FilePermission::user_write;
+  auto const file_permission = FilePermission::all_execute | FilePermission::all_write |
+                               FilePermission::all_read | FilePermission::group_execute |
+                               FilePermission::group_write | FilePermission::group_read |
+                               FilePermission::user_execute | FilePermission::user_write |
+                               FilePermission::user_read | FilePermission::directory;
 
   auto const all_execute = has<FilePermission::all_execute>(file_permission);
   auto const user_write  = has<FilePermission::user_write>(file_permission);