Arity

Arity is a language server, formatter, and linter for the R programming language, built in Rust on a lossless, incremental parser. It provides a fast, deterministic development experience that integrates with popular code editors and IDEs.

• Formatter --- deterministic, rule-based formatting toward the tidyverse style guide, with idempotent output and roxygen support.
• Linter --- a growing set of correctness, readability, and performance rules, many with safe autofixes.
• Language server --- formatting, diagnostics with quick fixes, hover, completion, signature help, go-to-definition and references, rename, document and workspace symbols, semantic tokens, folding, and call hierarchy.

Runs on Linux, macOS, and Windows (x86_64 and arm64).

Installation

Arity is available from several sources:

• crates.io --- cargo install arity
• npm --- npm install -g arity-cli (bundles a prebuilt binary)
• PyPI --- uv tool install arity / pipx install arity
• Prebuilt binaries --- from the releases page
• VS Code / Open VSX --- the Arity extension (also works in Positron)

From npm

Install with npx or npm:

# One-shot run, no install:
npx arity-cli format file.R

# Persistent install:
npm install -g arity-cli

The package detects your platform at install time and pulls in a prebuilt binary via npm's optional dependencies --- no Rust toolchain required.

From crates.io

If you have Rust installed:

cargo install arity

Formatter

To format your code, you can use:

• arity format [file]
• arity format --verify [file]
• arity format --check <path> [<path> ...]

Linter

To lint your code, you can use:

• arity lint <path> [<path> ...]

arity lint reads from stdin when given no paths, and exits non-zero when it reports any findings.

Configuration

Arity reads an optional arity.toml, discovered by walking up from each file's directory to the repository root. Run arity init to scaffold a commented starter file. See the configuration reference for every key.

Editor integration

arity lsp starts a stdio-based language server offering formatting, diagnostics with quick fixes, hover, completion, signature help, go-to-definition and references, rename, document and workspace symbols, semantic tokens, folding, and call hierarchy.

The Arity extension for VS Code / Open VSX (and Positron) bundles the binary and starts the server automatically. For Neovim, Helix, and other editors, see the editor setup guide.

Documentation

Full documentation lives at arity.cc:

• Getting started
• Editor setup
• Configuration
• CLI reference
• Lint rules