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README.qmd
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---
format: gfm
---
<!-- README.md is generated from README.qmd. Please edit that file -->
```{r}
#| include: false
knitr::opts_chunk$set(
collapse = TRUE,
comment = "#>",
# fig.path = "man/figures/README-",
out.width = "100%"
)
```
# Savvy - A simple R extension interface using Rust
<!-- badges: start -->
[](https://github.com/yutannihilation/savvy/actions/workflows/R-CMD-check.yaml)
[](https://crates.io/crates/savvy)
[](https://docs.rs/savvy/latest/)
[_%2F%C2%AF-green?style=flat-square&logo=docsdotrs&label=docs%20(dev)&labelColor=grey)](https://yutannihilation.github.io/savvy/reference/savvy/)
<!-- badges: end -->
**savvy** is a simple R extension interface using Rust, like the [extendr] framework.
The name "savvy" comes from the Japanese word "錆" (pronounced as `sàbí`), which means "Rust".
With savvy, you can automatically generate R functions from Rust code. This is
an example of what a savvy-powered function would look like:
**Rust**
``` rust
use savvy::savvy;
/// Convert to Upper-case
///
/// @param x A character vector.
/// @export
#[savvy]
fn to_upper(x: StringSexp) -> savvy::Result<savvy::Sexp> {
// Use `Owned{type}Sexp` to allocate an R vector for output.
let mut out = OwnedStringSexp::new(x.len())?;
for (i, e) in x.iter().enumerate() {
// To Rust, missing value is an ordinary value. In `&str`'s case, it's just "NA".
// You have to use `.is_na()` method to distinguish the missing value.
if e.is_na() {
// Set the i-th element to NA
out.set_na(i)?;
continue;
}
let e_upper = e.to_uppercase();
out.set_elt(i, e_upper.as_str())?;
}
out.into()
}
```
**R**
``` r
to_upper(c("a", "b", "c"))
#> [1] "A" "B" "C"
```
[extendr]: https://extendr.github.io/
## User guide
<https://yutannihilation.github.io/savvy/guide/>
## Contributing
[CONTRIBUTING.md](./CONTRIBUTING.md)
## Examples
A toy example R package can be found in [`R-package/` directory](https://github.com/yutannihilation/savvy/tree/main/R-package).
## Thanks
Savvy is not quite unique. This project is made possible by heavily taking
inspiration from other great projects:
* The basic idea is of course based on
[extendr](https://github.com/extendr/extendr/). Savvy would not exist without
extendr.
* [cpp11](https://cpp11.r-lib.org/)'s "writable" concept influenced the design a
lot. Also, I learned a lot from the great implementation such as [the
protection mechanism](https://cpp11.r-lib.org/articles/internals.html#protection).
* [PyO3](https://github.com/PyO3/pyo3) made me realize that the FFI crate
doesn't need to be a "sys" crate.