This repository contains several individual projects, which are evolving together.

• ark, the Ark R Kernel. Ark is a native kernel for R built on the Amalthea framework that interacts with the R interpreter in the same way RStudio does (i.e. it's implemented on top of the frontend API of R). It also implements the Language Server Protocol, using tower-lsp.

• harp, Rust wrappers for R objects and interfaces. This is intended as an internal utility library for Ark rather than a general purpose API for R like extendr.

• libr, our bindings to R. These are designed to be dynamically loaded using dlopen() on Unixes or LoadLibrary() on Windows. This is in contrast to libR-sys bindings which are meant to be used with R linked at build-time.

• amalthea, a Rust framework for building Jupyter and Positron kernels.

• echo, a toy kernel for a fictional language that can be used to experiment with the kernel framework without the nuisance of getting language bindings working. As the name implies, it is a language that just echoes its input back as output.

• stdext, extensions to Rust's standard library for utility use in the other internal projects.