Changelog

This changelog is generated automatically from GitHub Releases.

yaml12 0.2.0

2026-08-25 · GitHub

format_yaml() and write_yaml() now produce more human-readable YAML while preserving exact round trips:
- The new integer width argument defaults to 80 columns and wraps long strings at safe word boundaries. Pass None to disable wrapping.
- Strings are emitted without quotes when YAML 1.2 permits. Strings that the core schema would read as null, a boolean, or a number remain quoted, including arbitrary-sized decimal, octal, and hexadecimal integer strings.
- Multiline strings use readable folded or literal block styles when possible. Paragraph breaks, leading whitespace, empty lines, trailing newlines, and embedded document markers round-trip unchanged. Other multiline strings use a quoted fallback.
Mapping keys longer than YAML’s 1,024-character simple-key limit now use explicit key syntax.
Non-finite floats now use the canonical spellings .Inf, -.Inf, and .NaN while continuing to round-trip as floats.
write_yaml() and format_yaml(..., multi=True) no longer add optional document end (...) markers. Written documents still begin with --- and end with a newline.

By default, parse_yaml() and read_yaml() now preserve tags in the tag:yaml.org,2002: namespace that are not converted to built-in Python values in a Yaml wrapper. Explicit handlers still run when supplied.
The parser now accepts and ignores reserved directives such as %***, and treats indented --- text as part of a multiline plain scalar.
write_yaml() gains an append argument for adding complete YAML documents to a filesystem path. Its default behavior still replaces the file. read_yaml() and write_yaml() also expand paths beginning with ~ using os.path.expanduser().

Prebuilt wheels now include Intel macOS, Windows ARM64, and CPython 3.14 free-threaded builds. Free-threading support is currently beta. Source builds now require Rust 1.83 or newer.