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LuaJIT CPython Module

This project provides a Lua module that uses LuaJIT FFI to access an embedded CPython 3.11 library.

Prerequisites

  • macOS (tested on Apple Silicon)
  • LuaJIT
  • Clang/GCC
  • Make
  • Git

Installation

  1. Clone the repository (if you haven't already).

  2. Build CPython: The project includes a cpython submodule (or you can clone it manually).

    # Clone CPython 3.11 if not present
git clone --depth 1 --branch 3.11 https://github.com/python/cpython.git

# Configure and Build
cd cpython
./configure --enable-shared
make -j$(sysctl -n hw.ncpu)
cd ..

# Copy the shared library
cp cpython/libpython3.11.dylib cpython.so

Usage

  1. Ensure cpython.lua and cpython.so are in the same directory (or cpython.so is in a path accessible relative to cpython.lua).

  2. Require the module in your Lua script:

    local cpython = require("cpython")

-- Set the Python path to include the standard library and compiled modules
-- Adjust paths as necessary for your environment
local ffi = require("ffi")
local path = "./cpython/Lib:./cpython/build/lib.macosx-26.1-arm64-3.11"
local wchar_path = ffi.new("wchar_t[?]", #path + 1)
for i = 1, #path do
    wchar_path[i-1] = string.byte(path, i)
end
wchar_path[#path] = 0

cpython.Py_SetPath(wchar_path)

-- Unset PYTHONPATH/PYTHONHOME to avoid conflicts with system Python
ffi.cdef[[ int unsetenv(const char *name); ]]
ffi.C.unsetenv("PYTHONPATH")
ffi.C.unsetenv("PYTHONHOME")

cpython.Py_Initialize()
cpython.PyRun_SimpleString("print('Hello from Python!')")
cpython.Py_Finalize()

Running the Demo

To run the example script, execute the following command in your terminal:

luajit "CPython Demo.lua"

Files

  • cpython.lua: The Lua module definition.
  • cpython.so: The compiled CPython shared library.
  • CPython Demo.lua: An example script demonstrating usage.

Distribution

To distribute this module or move it to another location, you need to copy the following:

  1. cpython.lua
  2. cpython.so
  3. The Python Standard Library (Lib folder from the cpython source).
  4. The compiled Python modules (located in cpython/build/lib.macosx-...).

You should organize them such that cpython.lua can find cpython.so, and the Python initialization code (like in CPython Demo.lua) can point Py_SetPath to the Lib folder and the compiled modules folder.

Troubleshooting

  • Import Errors: If Python cannot find standard modules, you may need to set PYTHONHOME or ensure the Lib directory from the CPython source is accessible.
  • Architecture Mismatch: Ensure both LuaJIT and the compiled cpython.so are built for the same architecture (e.g., arm64 on Apple Silicon).

Sample Output:

luajit "Py Demo.lua"
Hello from Python! sys.version: 3.11.14+ (heads/3.11:3b7d81d, Nov 24 2025, 05:34:08) [Clang 17.0.0 (clang-1700.4.4.1)]
sys.path: ['/Users/vfx/Desktop/LuaJIT CPython Lua Module/cpython/Lib', '/Users/vfx/Desktop/LuaJIT CPython Lua Module/cpython/build/lib.macosx-26.1-arm64-3.11']
Initializing Python...
Python Version:
3.11.14+ (heads/3.11:3b7d81d, Nov 24 2025, 05:34:08) [Clang 17.0.0 (clang-1700.4.4.1)]

Running Python code:

Finalizing Python...
Done.