User Guide

A comprehensive guide to using extendr

This user guide focuses on developing R packages that call Rust code and publishing them to CRAN. A basic understanding of Rust is assumed. If you are new to Rust, start with the Rust Basics section.

Core Concepts

• The #[extendr] macro: How to expose Rust functions and structs to R.
• R to Rust type mapping: An overview of how R types map to extendr types.
• Conversion to and from R data: Converting between R and Rust values using From, Into, and TryFrom.

Type Mapping

• Scalar Type Mapping: Working with R scalar values in Rust.
• Vector Type Mapping: Working with R vectors in Rust.
• Using HashMaps: Working with R named lists and Rust HashMaps.
• Rust Structs to Lists: Exposing Rust structs as R lists.
• Default function arguments: Handling optional and default arguments.

Integrations

• serde integration: Serializing and deserializing Rust types with serde.
• Async with Tokio: Using async Rust with Tokio inside extendr.
• Building for WebR: Compiling extendr packages for WebR.

Publishing

• Publishing to CRAN: Steps and considerations for submitting an extendr package to CRAN.
• CRAN’s Rust versions: Understanding CRAN’s minimum supported Rust version policy.

FAQ

• Frequently Asked Questions

What’s not in this guide?

This guide is not a comprehensive introduction to Rust. Concepts are introduced only to explain extendr tools. To learn more about Rust, consult “The Book”.

This guide is also not a comprehensive guide to R package development. Better resources exist for that, notably R Packages (2e). We will point you to relevant external resources as needed.

Software requirements

This guide assumes the following versions of necessary software:

• R: 4.2
• Rust 1.65.0
• extendr-api 0.8.1
• rextendr 0.4.2.9000

Please see Get Started if you have not already installed this software.