yamlcore
YAML 1.2 Support for PyYAML
Decision gist · record as of 2026-08-14
Yes, if you need YAML 1.2 Core Schema compliance and PyYAML hasn't yet merged native support. The package is low-friction to install, carries no security issues, and solves a real spec-compliance gap. However, check whether the pending PyYAML PR has been merged in your target PyYAML version first—if it has, use PyYAML's native support instead. The dormant maintenance status is acceptable for a thin compatibility layer, but monitor for PyYAML API changes.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires PyYAML to be installed; Python 3.6 or later.
- Low friction: pure Python wheel with a single runtime dependency on PyYAML.
- Dormant maintenance (674 days since last release, last commit 2024-10-11) but marked Production/Stable and carrying no known vulnerabilities.
License · maintenance · safety
permissive license (permissive) — MIT License permits unrestricted use, modification, and distribution with minimal obligations—suitable for both open-source and commercial projects.
last release 2024-10-09 (674 days) · last repo commit 2024-10-11 · 18 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 258,593 downloads/mo, #8,428 on PyPI
Alternatives
Verify before relying
from yamlcore import CoreLoader, CoreDumper
y = """---
core:
- true
- 0o10
- 0x42
- ~
"""
d = CoreLoader().get_single_data(y)
out = CoreDumper().represent(d)- Whether the pending PyYAML PR #555 has since been merged, potentially making this package obsolete.
- Performance characteristics compared to PyYAML's default loader on large YAML files.
- Compatibility with PyYAML versions beyond those tested at release time.
- Exact usage patterns for CoreLoader and CoreDumper integration with PyYAML.
What it is and what it does
yamlcore extends PyYAML to parse YAML 1.2 files using the Core Schema specification, which differs from PyYAML's default YAML 1.1 behavior in how it interprets types and handles edge cases. For example, strings like 'yes' and 'no' remain strings in YAML 1.2 (not booleans), and numeric literals like '0x42' and '0o10' are correctly parsed as hex and octal. The package enforces the YAML spec's requirement that duplicate keys are forbidden, catching accidental key collisions that PyYAML would silently allow.
It inherits from PyYAML rather than forking it, providing CoreLoader and CoreDumper classes that work alongside the standard PyYAML module. The package also offers C-accelerated variants (CCoreLoader, CCoreDumper) for users with libyaml installed. It is designed as a stopgap until PyYAML itself adds YAML 1.2 support, which has been pending in a pull request.
Use it for
- Loading YAML 1.2 configuration files where strict type interpretation matters (e.g., distinguishing 'yes' as a string, not a boolean).
- Catching duplicate keys in YAML documents during parsing to prevent silent data loss.
- Migrating from YAML 1.1 to YAML 1.2 while keeping the rest of your PyYAML workflow intact.
- Parsing hexadecimal and octal literals correctly as per YAML 1.2 spec (0x42, 0o10).
- Dumping YAML with Core Schema compliance using CoreDumper.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes, if you need YAML 1.2 Core Schema compliance and PyYAML hasn't yet merged native support.
The package is low-friction to install, carries no security issues, and solves a real spec-compliance gap. However, check whether the pending PyYAML PR has been merged in your target PyYAML version first—if it has, use PyYAML's native support instead. The dormant maintenance status is acceptable for a thin compatibility layer, but monitor for PyYAML API changes.
Install
yamlcore on PyPI
Before you install
Low friction: pure Python wheel with a single runtime dependency on PyYAML. Dormant maintenance (674 days since last release, last commit 2024-10-11) but marked Production/Stable and carrying no known vulnerabilities.
Requires PyYAML to be installed; Python 3.6 or later.
License in practice
MIT License permits unrestricted use, modification, and distribution with minimal obligations—suitable for both open-source and commercial projects.
Quickstart
from yamlcore import CoreLoader, CoreDumper
y = """---
core:
- true
- 0o10
- 0x42
- ~
"""
d = CoreLoader().get_single_data(y)
out = CoreDumper().represent(d)Verify before relying
- Whether the pending PyYAML PR #555 has since been merged, potentially making this package obsolete.
- Performance characteristics compared to PyYAML's default loader on large YAML files.
- Compatibility with PyYAML versions beyond those tested at release time.
- Exact usage patterns for CoreLoader and CoreDumper integration with PyYAML.
Package facts
| License | permissive license permissive |
| Python support | Supports the current Python release >=3.6 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 1 packagePyYAML |
| Maintenance | Dormant 674 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 258,593 / month, #8,428 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 5 - Production/StableIntended Audience :: DevelopersLicense :: OSI Approved :: MIT LicenseOperating System :: OS IndependentProgramming Language :: Python :: 3 |
Evidence: yamlcore-0.0.4-py3-none-any.whl
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