ryaml is a Python library that wraps a Rust yaml parser, serde-yaml, to quickly and safely parse and dump yaml to and from Python objects.

It is not compatible with PyYAML, and it has a similar design to the json module. Furthermore PyYAML implements version 1.1 of the yaml spec whereas ryaml implements version 1.2 of the spec.

Notable differences between version 1.1 and 1.2 are

• YAML 1.2 dropped support for several features unquoted Yes, No, On, Off
• YAML 1.2 no longer accepts strings that start with a 0 and solely consist of number characters as octal, you need to specify such strings with 0o[0-7]+ (zero + lower-case o for octal + one or more octal characters).
• YAML 1.2 no longer supports sexagesimals <https://en.wikipedia.org/wiki/Sexagesimal>_, so the string scalar 12:34:56 doesn't need quoting.
• \/ escape for JSON compatibility
• correct parsing of floating point scalars with exponentials

The hope is this will be used as a safe and fast yaml parser in lieu of PyYAML.

We ship binary wheels for Windows, Linux, and macOS, so as long as you are using Python 3.10+, you can run:

$ python -m pip install ryaml

Otherwise, you will need to build from source. To do so, first install Rust 1.41 stable.

Then you should be able to just

$ git clone https://github.com/emmatyping/ryaml
$ cd ryaml
$ python -m pip install .

Or if you want to build a wheel:

$ git clone https://github.com/emmatyping/ryaml
$ cd ryaml
$ python -m pip install maturin
$ maturin build --release --no-sdist
# OR if you want an abi3 wheel (compatible with Python 3.10+)
$ maturin build --release --no-sdist --cargo-extra-args="--features=abi3"

And a wheel will be created in target/wheels which you can install.

The API of ryaml is very similar to that of json in the standard library:

You can use ryaml.loads to read from a str:

import ryaml
obj = ryaml.loads('key: [10, "hi"]')
assert isinstance(obj, dict) # True
assert obj['key'][1] == "hi" # True

And ryaml.dumps to dump an object into a yaml file:

import ryaml
s = ryaml.dumps({ 'key' : None })
print(s)
# prints:
# ---
# key: ~

There are also ryaml.load and ryaml.load_all to read yaml document(s) from files:

import ryaml
obj = {'a': [{'b': 1}]}
with open('test.yaml', 'w') as w:
    ryaml.dump(w, obj)
with open('test.yaml', 'r') as r:
    assert ryaml.load(r) == obj
with open('multidoc.yaml', 'w') as multi:
    multi.write('''
---
a:
  key:
...
---
b:
  key:
    ''')
with open('multidoc.yaml', 'r') as multi:
    docs = ryaml.load_all(multi)
assert len(docs) == 2
assert docs[0]['a']['key'] is None

ryaml.load_all will, as seen above, load multiple documents from a single file.

This project is standing on the shoulders of giants, and would not be possible without:

pyo3

serde-yaml

yaml-rust

pyo3-file

pythonize