emacs-module-rs provides high-level Rust binding and tools to write Emacs's dynamic modules. It is easy to use if you know either Rust or Emacs.

It currently supports:

  • Stable Rust 1.56+.
  • Emacs 25 or above, built with module support.
  • macOS, Linux, Windows.

Setting up

  • Install the Rust toolchain with rustup.
  • Make sure that your Emacs was compiled with module support. Check that module-file-suffix is not nil, and the function module-load is defined.
    • On macOS, the recommended installation method is MacPorts (emacs-app and emacs-mac-app).
    • On Windows, the recommended installation method for older Emacs versions (before 27.2) is pacman -S mingw-w64-x86_64-emacs (msys2), as the archives on GNU FTP's server were built without module support.


  • On Windows, only Rust's msvc toolchain was confirmed to work, not the gnu toolchain.
  • When the optional feature bindgen is enabled, the raw binding will be generated from emacs-module.h at build time. Therefore you will also need to install clang. (This is recommended only for troubleshooting, though.) For example, on Windows:
    # In Powershell
    scoop install llvm
    $env:LIBCLANG_PATH = "$(scoop prefix llvm)\bin"
    cargo build --all

Known Issues

There is a bug (see issue #1) with Emacs 26 on Linux that prevents it from loading any dynamic modules (even those written in C), if:

  • Emacs is built without thread support.
  • The OS is Ubuntu 16.04 (Xenial).