sexpdata
S-expression parser for Python
Decision gist · record as of 2026-08-14
Yes, if you need S-expression parsing. The package is simple, dependency-free, and permissively licensed. However, be aware that it is aging—no release in 948 days—so if you encounter bugs or need new features, maintenance may be slow. For basic S-expression I/O with stable Python versions, it is a reasonable choice.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Low friction installation with no runtime dependencies.
- Maintenance is aging—last release was 948 days ago, though the repository remains active with a recent commit on 2025-09-18 and 111 stars.
License · maintenance · safety
permissive license (permissive) — BSD 2-Clause License is permissive; you may use, modify, and distribute the package freely in commercial or private projects provided you retain the license notice and disclaimer.
last release 2024-01-09 (948 days) · last repo commit 2025-09-18 · 111 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 139,401 downloads/mo, #11,301 on PyPI
Alternatives
Verify before relying
pip install sexpdata
from sexpdata import loads, dumps
data = loads('("a" "b")')
print(data) # ['a', 'b']
print(dumps(['a', 'b'])) # ("a" "b")- Whether the parser handles nested or complex S-expressions beyond the simple example shown.
- Performance characteristics or limits for large or deeply nested expressions.
- Whether round-trip fidelity (parse then serialize) is guaranteed for all valid inputs.
What it is and what it does
sexpdata is a lightweight S-expression parser and serializer for Python. It reads Lisp-style symbolic expressions (nested lists and quoted strings) from text and converts them to Python lists and strings, or does the reverse—turning Python data structures back into S-expression text. The API mirrors familiar serialization libraries like `json` and `pickle`, with simple `loads`/`dumps` functions for string data and `load`/`dump` for file I/O.
The package has no runtime dependencies and supports Python 3.7 through 3.12. It is classified as Alpha-stage software and has not seen a release in some time, though the repository remains minimally maintained. Use it when you need to exchange data with Lisp systems, parse configuration files in S-expression format, or work with symbolic data structures in a Python context.
Use it for
- Parse Lisp or Scheme configuration files and convert them to Python data for processing.
- Serialize Python data structures to S-expression format for exchange with Lisp-based tools.
- Read symbolic expressions from text and manipulate them as nested Python lists.
- Build a bridge between Python and Emacs Lisp or other Lisp dialects for interop.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes, if you need S-expression parsing.
The package is simple, dependency-free, and permissively licensed. However, be aware that it is aging—no release in 948 days—so if you encounter bugs or need new features, maintenance may be slow. For basic S-expression I/O with stable Python versions, it is a reasonable choice.
Install
sexpdata on PyPI
Before you install
Low friction installation with no runtime dependencies. Maintenance is aging—last release was 948 days ago, though the repository remains active with a recent commit on 2025-09-18 and 111 stars.
License in practice
BSD 2-Clause License is permissive; you may use, modify, and distribute the package freely in commercial or private projects provided you retain the license notice and disclaimer.
Quickstart
pip install sexpdata
from sexpdata import loads, dumps
data = loads('("a" "b")')
print(data) # ['a', 'b']
print(dumps(['a', 'b'])) # ("a" "b")Verify before relying
- Whether the parser handles nested or complex S-expressions beyond the simple example shown.
- Performance characteristics or limits for large or deeply nested expressions.
- Whether round-trip fidelity (parse then serialize) is guaranteed for all valid inputs.
Package facts
| License | permissive license permissive |
| Python support | Supports the current Python release >=3.7 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | None |
| Maintenance | Aging 948 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 139,401 / month, #11,301 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 3 - AlphaLicense :: OSI Approved :: BSD LicenseProgramming Language :: Emacs-LispProgramming Language :: LispProgramming Language :: PythonProgramming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.7Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9 |
Evidence: sexpdata-1.0.2-py3-none-any.whl
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