.. _mlx_in_cpp:

Using MLX in C++

You can use MLX in a C++ project with CMake.

.. note::

This guide is based one the following example using MLX in C++ <https://github.com/ml-explore/mlx/tree/main/examples/cmake_project>_

First install MLX:

.. code-block:: bash

pip install -U mlx

You can also install the MLX Python package from source or just the C++ library. For more information see the :ref:documentation on installing MLX <build_and_install>.

Next make an example program in example.cpp:

.. code-block:: C++

#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; }

The next step is to setup a CMake file in CMakeLists.txt:

.. code-block:: cmake

cmake_minimum_required(VERSION 3.27)

project(example LANGUAGES CXX)

set(CMAKE_CXX_STANDARD 20) set(CMAKE_CXX_STANDARD_REQUIRED ON)

Depending on how you installed MLX, you may need to tell CMake where to find it.

If you installed MLX with Python, then add the following to the CMake file:

.. code-block:: cmake

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)

If you installed the MLX C++ package to a system path, then CMake should be able to find it. If you installed it to a non-standard location or CMake can't find MLX then set MLX_ROOT to the location where MLX is installed:

.. code-block:: cmake

set(MLX_ROOT "/path/to/mlx/")

Next, instruct CMake to find MLX:

.. code-block:: cmake

find_package(MLX CONFIG REQUIRED)

Finally, add the example.cpp program as an executable and link MLX.

.. code-block:: cmake

add_executable(example example.cpp) target_link_libraries(example PRIVATE mlx)

You can build the example with:

.. code-block:: bash

cmake -B build -DCMAKE_BUILD_TYPE=Release cmake --build build

And run it with:

.. code-block:: bash

./build/example

Note find_package(MLX CONFIG REQUIRED) sets the following variables:

.. list-table:: Package Variables :widths: 20 20 :header-rows: 1

• • Variable
  • Description
• • MLX_FOUND
  • True if MLX is found
• • MLX_INCLUDE_DIRS
  • Include directory
• • MLX_LIBRARIES
  • Libraries to link against
• • MLX_CXX_FLAGS
  • Additional compiler flags
• • MLX_BUILD_ACCELERATE
  • True if MLX was built with Accelerate
• • MLX_BUILD_METAL
  • True if MLX was built with Metal