Minimal Example of Calling Rust from R using Cargo
Rust is a modern alternative to C and compiled rust code is ABI compatible with C. Many Rust libraries include C API headers so that the compiled rust code can be called from R/C/C++ as if it were C code.
The standard rust toolchain includes a great package manager
cargo with a corresponding registry crates.io. Cargo makes it very easy to build a rust package including all dependencies into a static library that can easily be linked into an R package.
This is perfect for R because we can compile and link all rust code at build-time without any system dependencies. Rust itself has no substantial runtime so the resulting R package is entirely self contained. Indeed, rust has been designed specifically to serve well as an embedded language.
Simply bundle your rust code into a cargo package (just add a
Cargo.toml file) and then invoke the build + link as shown in src/Makevars.
hellorust ├─ configure ← checks if 'cargo' is installed ├─ src │ ├─ myrustlib ← bundled cargo package with your code │ | ├─ Cargo.toml ← cargo dependencies and metadata │ | ├─ src ← rust source code │ | └─ api.h ← C headers for exported rust API | | │ ├─ Makevars ← Ties everything together │ └─ wrapper.c ← C code for R package ├─ DESCRIPTION └─ R ← Standard R+C stuff
cargo is only needed at build-time. Rust has no runtime dependencies. To install on MacOS use homebrew:
brew install rust
And on Debian/Ubuntu:
sudo apt-get install cargo
And on Fedora / CentOS:
sudo yum install cargo
And on Arch:
sudo pacman -Sy cargo
On CentOS you first need to enable EPEL via
sudo yum install epel-release.
In order for rust to work with R you need to install the toolchain using
rustup and then add the
i686-pc-windows-gnu targets. First download rustup-init.exe and then install the default toolchain:
rustup-init.exe -y --default-host x86_64-pc-windows-gnu
To compile 32bit packages also add the i686 target:
rustup target add i686-pc-windows-gnu