MLX in C++ example (#1736)

* MLX in C++ example

* nits

* fix docs

examples/cmake_project/CMakeLists.txt

@@ -0,0 +1,22 @@
+cmake_minimum_required(VERSION 3.27)
+
+project(example LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+# Comment the following two commands only the MLX C++ library is installed and
+# set(MLX_ROOT "/path/to/mlx") directly if needed.
+find_package(
+  Python 3.9
+  COMPONENTS Interpreter Development.Module
+  REQUIRED)
+execute_process(
+  COMMAND "${Python_EXECUTABLE}" -m mlx --cmake-dir
+  OUTPUT_STRIP_TRAILING_WHITESPACE
+  OUTPUT_VARIABLE MLX_ROOT)
+
+find_package(MLX CONFIG REQUIRED)
+
+add_executable(example example.cpp)
+target_link_libraries(example PRIVATE mlx)

examples/cmake_project/README.md

@@ -0,0 +1,26 @@
+## Build and Run 
+
+Install MLX with Python:
+
+```bash
+pip install mlx>=0.22
+```
+
+Build the C++ example:
+
+```bash
+cmake -B build -DCMAKE_BUILD_TYPE=Release
+cmake --build build
+```
+
+Run the C++ example:
+
+```
+./build/example
+```
+
+which should output:
+
+```
+array([2, 4, 6], dtype=int32)
+```

examples/cmake_project/example.cpp

@@ -0,0 +1,14 @@
+// Copyright © 2024 Apple Inc.
+
+#include <iostream>
+
+#include "mlx/mlx.h"
+
+namespace mx = mlx::core;
+
+int main() {
+  auto x = mx::array({1, 2, 3});
+  auto y = mx::array({1, 2, 3});
+  std::cout << x + y << std::endl;
+  return 0;
+}