larzyaml

A practical YAML subset — load and dump. Pure Python, zero dependencies.

Covers the YAML people actually write for config: nested mappings and sequences, plain and quoted scalars with type inference, inline flow collections, and # comments — the 95% that config files use, without a dependency.

from larzyaml import load, dump

load("""
name: myapp
port: 8080
debug: true
hosts:
  - a.com
  - b.com
db: {host: localhost, port: 5432}
""")
# {'name': 'myapp', 'port': 8080, 'debug': True,
#  'hosts': ['a.com', 'b.com'], 'db': {'host': 'localhost', 'port': 5432}}

Why

• No dependency. PyYAML pulls in a C extension (or a big pure-Python parser); larzyaml is a few hundred readable lines for the common cases.
• The config subset, done right. Nested maps/sequences by indentation, sequence-of-maps (- key: value), typed scalars (1, 2.5, true, null), inline [...]/{...}, and quote-aware comment stripping.
• Round-trips. dump() re-serializes, quoting ambiguous strings ("true", "123") so they load back as strings.

Not the full spec — no anchors, tags, or block scalars. For config files, fixtures, and simple data, that's exactly enough. Pairs with larzconf.

Install

pip install larzyaml

Usage

from larzyaml import load, dump
data = load(open("config.yaml").read())
text = dump({"name": "app", "hosts": ["a", "b"], "db": {"port": 5432}})

Tests

python -m unittest discover -s tests -v   # 18 tests incl. dump round-trips

The Larz stack

One of 30+ pure-Python, zero-dependency libraries at github.com/larz-scripter.

License

MIT © larz-scripter