extendr-bindings

name	extendr-bindings
description	extendr conventions for exposing a Rust core to R: extendr macros and module registration, Robj type mapping, NA handling, rextendr builds, R package scaffolding, and CRAN compliance. Load when generating or reviewing extendr R bindings for a Rust library.

• Use extendr crate for Rust-R interop. #[extendr] macro on functions, extendr_module! for registration.
• Type mapping: Robj for generic R objects, Doubles, Integers, Strings, List for typed access.
• Return Result<T, extendr_api::Error> for R error propagation. Use .into() for Rust-to-R conversion.
• NA handling: use Rfloat::na(), Rint::na() for missing values. Check with .is_na() before operations.
• Build with rextendr::document() in R for development, cargo build --release for production.
• Package integration: use usethis::use_extendr() for scaffolding. Maintain src/rust/ in R package.
• Test R-side with testthat, Rust-side with standard #[test]. Use rextendr::test() for integration.
• CRAN compliance: R CMD check --as-cran must pass. No compiler warnings. Vendor Rust dependencies.
• Keep R wrapper functions thin — heavy computation in Rust, R provides user-facing API with roxygen2 docs.
• Anti-patterns: ignoring NA values, allocating R objects in Rust threads, panics in #[extendr] functions.