# egraphs-good/egg

egg is a flexible, high-performance e-graph library

Repository: https://github.com/egraphs-good/egg
Canonical: https://ross.abutalabs.com/products/egraphs-good-egg
Homepage: https://egraphs-good.github.io
Language: Rust
License: MIT
License Family: permissive
Last push: 2026-07-19T16:48:21+00:00

## Health v2 (maintenance only)
Score: 74/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 93, release rhythm 35, longevity 100
- inputs: {"age_days": 2687, "days_push": 45, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1822, forks 201 (observed 2026-08-28T04:05:41.122096+00:00)

## What it is
egg is a Rust library implementing e-graphs and equality saturation, providing a fast and flexible data structure for compactly representing many equivalent expressions. It is used to build program optimizers, synthesizers, verifiers, and other tools based on rewrite rules.

## Use cases
- build a program optimizer using equality saturation
- implement an e-graph data structure in Rust
- write a compiler pass that applies rewrite rules
- build a program synthesizer or verifier
- symbolic math simplification with rewrite rules
- partial evaluation of a lambda calculus

## When to choose
- you need a high-performance, hackable e-graph library in Rust
- you want to experiment with equality saturation for optimization or synthesis
- you prefer a simpler library design over a Datalog-based system

## When to avoid
- you want a language-based, Datalog-driven approach with incremental execution - use egglog instead
- you need Python bindings out of the box
- your project has nothing to do with term rewriting or equivalence reasoning

## Facets
- artifact type: library
- maturity: active
- function: parser, compiler, interpreter, developer-tools
- domain: compilers, programming-languages, developer-tools
- platform: rust, cross-platform
- tags: e-graphs, equality-saturation, term-rewriting, program-optimization, program-synthesis, smt, rust-library, algorithms, research

## Member repositories
- egraphs-good/egg (main) score 74

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:41.122096+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 2026-08-30T03:19:48.327107+00:00, confidence not recorded.
  - readme: https://github.com/egraphs-good/egg (fetched 2026-08-28T04:05:41.122096+00:00, sha 76667e9f1e5b)
  - homepage: https://egraphs-good.github.io (fetched 2026-08-29T10:58:47.976884+00:00, sha 06f9d3e596f6)
  - registry_crates: https://crates.io/api/v1/crates/egg (fetched 2026-08-29T10:58:47.986668+00:00, sha b89895afd438)
- Data as of 2026-08-30T08:39:29.467469+00:00.