# dabeaz/ply

Python Lex-Yacc

Repository: https://github.com/dabeaz/ply
Canonical: https://ross.abutalabs.com/products/ply
Homepage: http://www.dabeaz.com/ply/index.html
Language: Python
License Family: other
Archived: true
Last push: 2025-12-21T16:17:40+00:00

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 58, release rhythm 35, longevity 100
- inputs: {"age_days": 5722, "days_push": 255, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases, archived, no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2909, forks 477 (observed 2026-08-28T04:07:29.163080+00:00)

## What it is
PLY is a pure-Python, zero-dependency implementation of the classic lex and yacc parsing tools, providing lexing and LALR(1) parsing. It is used to build parsers for programming languages, ASTs, one-pass compilers, and protocol decoders.

## Use cases
- write a parser for a programming language in python
- build an abstract syntax tree from a grammar
- implement a lexer and LALR(1) parser without dependencies
- decode a custom protocol or DSL
- learn how lex and yacc style parsing works
- build a simple one-pass compiler in python

## When to choose
- you want a faithful, minimal lex/yacc experience in pure Python with no dependencies
- you're teaching or learning compiler construction
- you need a small parser you can vendor directly into your project

## When to avoid
- you need a maintained library - the author officially abandoned the project in December 2025
- you want modern parser-combinator or PEG ergonomics
- you need package-manager installation or long-term support guarantees

## Facets
- artifact type: library
- maturity: abandoned
- function: parser, compiler, developer-tools
- domain: parsers, programming-languages, compilers, developer-tools
- platform: python, cross-platform
- tags: lex, yacc, lalr, lexer, parser-generator, zero-dependency, compiler-construction

## Member repositories
- dabeaz/ply (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:29.163080+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 2026-08-29T18:48:13.304518+00:00, confidence not recorded.
  - readme: https://github.com/dabeaz/ply (fetched 2026-08-28T04:07:29.163080+00:00, sha 38570b8eccf6)
  - homepage: http://www.dabeaz.com/ply/index.html (fetched 2026-08-29T09:49:36.734974+00:00, sha a36da5a09a02)
  - site_page: http://www.dabeaz.com/ply/ply.html (fetched 2026-08-29T09:49:36.744381+00:00, sha cba2fd4f5e47)
- Data as of 2026-08-30T08:39:29.467469+00:00.