Python PEP Number Validator

PEP: how Python evolves, one proposal at a time

A PEP (Python Enhancement Proposal) is the formal document used by the Python community to discuss and adopt language changes, new libraries, processes and conventions. PEPs are deliberately modelled on the IETF's RFC tradition, but scoped to Python: anything from a new syntax feature to a packaging metadata field passes through a PEP before landing in CPython. This validator checks the PEP NNN format and helps you locate well-known proposals.

The process itself is defined by PEP 1, written in 2000 by Barry Warsaw, Jeremy Hylton and David Goodger. It documents the meta-rules: how to submit, how the discussion runs on python-dev, how the Steering Council (formerly the BDFL, Guido van Rossum, who retired the role in 2018) decides Accepted/Rejected/Deferred, and where the implementation lives.

Format and validation rule

A PEP identifier is the literal string PEP followed by a positive integer (no leading zeros, no upper bound, currently in the high 700s). The validator can also accept the bare number. Canonical regex:

/^PEP\s?\d{1,4}$/i        // PEP 8, PEP484, pep 695
/^\d{1,4}$/               // bare number: 8

Like RFCs, PEPs have no checksum: existence is the only check, and it requires a lookup in peps.python.org. Numbers are never reused — withdrawn or rejected PEPs keep their slot forever.

PEP types: Standards Track, Informational, Process

• Standards Track — proposes a new feature for the language or stdlib (PEP 484 type hints, PEP 572 walrus operator :=).
• Informational — gives guidance or background (PEP 20 The Zen of Python).
• Process — describes how the community works (PEP 1 itself, PEP 8000-series on governance).

Each PEP has a Status field that flows: Draft -> Accepted -> Final (or Rejected, Withdrawn, Deferred, Superseded). Process and Informational PEPs may sit at Active indefinitely.

Famous PEPs every Pythonista should know

• PEP 8 — Style Guide. 4-space indentation, snake_case for functions, max line length 79 (or 99 in modern projects). Enforced by ruff, flake8, black.
• PEP 20 — The Zen of Python (import this in any REPL).
• PEP 257 — Docstring conventions.
• PEP 333 / 3333 — WSGI, the gateway between web servers and Python apps.
• PEP 484 — type hints (2014), the foundation of mypy, pyright and modern Python typing.
• PEP 517 / 518 / 621 — the pyproject.toml ecosystem: build system, backend selection, core project metadata.
• PEP 572 — the walrus operator :=, controversial enough that it triggered Guido's retirement as BDFL.
• PEP 695 — generic syntax (class Stack[T]:) shipped in Python 3.12.
• PEP 703 — making the GIL optional. Available as an experimental build in Python 3.13 (Oct 2024).

Governance: BDFL, Steering Council, python-dev

From 1991 to 2018 Python had a BDFL (Benevolent Dictator For Life) — Guido van Rossum — who had the final word on every PEP. After the walrus operator fight (PEP 572) Guido resigned and the community adopted a Steering Council elected yearly under PEP 13. Discussion happens on discuss.python.org (replacing the legacy python-dev mailing list).

PEP vs RFC vs JEP

• PEP — Python only, scoped to language + stdlib + packaging.
• RFC — IETF, governs Internet protocols and is consumed by all languages.
• JEP — Java Enhancement Proposal, Oracle/OpenJDK equivalent for the JVM.
• TC39 proposals — JavaScript's equivalent, staged 0 through 4.
• RFCs/SIPs — Rust and Scala each maintain their own RFC repos with the same spirit.

Tooling and enforcement

PEP 8 is enforced by linters (ruff, flake8) and formatters (black, autopep8). Type hints from PEP 484 are checked by mypy, pyright/Pylance and pyre. Packaging PEPs (517, 518, 621) are implemented by pip, uv, hatchling and poetry. In the Brazilian community, python.org.br, the Python Brasil conference and the local GruPys (Grupy-SP, Grupy-RJ) help newcomers navigate the PEP landscape.

FAQ

Are PEPs free to read?

Yes. All PEPs are public-domain HTML at peps.python.org, generated from a Git repository under the Python Software Foundation umbrella.

Is PEP 8 mandatory?

It is a convention, but in practice every Python project enforces it through CI. Modern tools like ruff can autofix most violations in milliseconds. CPython itself follows PEP 8 strictly.

What is the current stable Python?

Python 3.13 (released October 2024) is the latest stable. It ships the experimental free-threaded build from PEP 703 and a new JIT preview from PEP 744. Python 3.14 is in alpha at the time of writing.

Was PEP 1 ever superseded?

PEP 1 still describes the process today, with minor revisions. PEP 12 defines the formatting template for new PEPs (reStructuredText / Markdown). They complement each other rather than supersede.

Can anyone submit a PEP?

Yes. The workflow is: discuss on discuss.python.org until rough consensus emerges, find a sponsor among core devs, open a pull request against the python/peps repo, and await the Steering Council decision. Most rejected PEPs are rejected for lacking implementation effort, not for the idea itself.