# mattwparas/steel

An embedded scheme interpreter in Rust

Repository: https://github.com/mattwparas/steel
Canonical: https://ross.abutalabs.com/products/steel
Language: Rust
License: Apache-2.0
License Family: permissive
Topics: rust, racket, transducers, scripting-language, contracts, programming-language, lisp, scheme
Last push: 2026-08-25T03:54:49+00:00

## Health v2 (maintenance only)
Score: 89/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 71, longevity 100
- inputs: {"age_days": 2386, "days_push": 8, "days_rel": 193, "gap_med": 9, "n_releases_24m": 2}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2546, forks 135 (observed 2026-08-28T04:07:00.240483+00:00)

## What it is
Steel is an embeddable Scheme dialect interpreter implemented in Rust, running on a bytecode virtual machine with mostly R5RS compliance. It includes a standalone REPL/CLI interpreter, a package manager, and a language server, and integrates easily with native Rust functions and structs.

## Use cases
- embed a scripting language in a Rust application
- script my Rust program with a scheme interpreter
- try scheme in the browser
- learn scheme with a modern REPL
- call Rust functions from a lisp script
- extend an app with user-defined macros and contracts

## When to choose
- you need an embeddable scripting language in Rust with native FFI
- you want a mostly R5RS-compliant scheme with modules and macros
- you want a standalone scheme REPL plus language server

## When to avoid
- you need full R7RS compliance or let-syntax today
- you need a battle-tested pre-1.0-stable API for production
- you need a mature ecosystem like Guile or Racket

## Facets
- artifact type: cli-tool
- maturity: active
- function: interpreter, programming-language, cli, sdk
- domain: programming-languages, developer-tools
- platform: rust, cross-platform, cli, wasm
- tags: scheme, lisp, embedded-scripting, bytecode-vm, r5rs, repl, language-server, transducers, contracts, interpreter, command-line

## Member repositories
- mattwparas/steel (main) score 89

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:00.240483+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T08:31:48.392385+00:00, confidence not recorded.
  - readme: https://github.com/mattwparas/steel (fetched 2026-08-28T04:07:00.240483+00:00, sha 048f99bcc4d8)
- Data as of 2026-08-30T08:39:29.467469+00:00.