Changelog

Source: NEWS.md

frontmatter 0.2.0

• New format_front_matter() and write_front_matter() functions for serializing documents with YAML or TOML front matter. These are the inverse of parse_front_matter() and read_front_matter(), enabling full roundtrip support. Supports all delimiter formats including standard (---, +++), comment-wrapped (# ---, #' ---), and PEP 723. Note that the roundtrip is not perfect; comments and formatting within the front matter content may not be preserved.

• parse_front_matter() and read_front_matter() now attach format and fence_type as attributes to the returned list, making it easier to preserve the original format when rewriting documents.

• Fixed an issue with parsing front matter in comment-prefixed formats (e.g., R and Python files) where the body content was not preserved correctly. The body is now retained as-is, after stripping any leading comment-prefixed empty lines.

frontmatter 0.1.0

CRAN release: 2026-01-14

• Initial CRAN release.

• Extract and parse YAML or TOML front matter from text documents with read_front_matter() or parse_front_matter().

• Support for multiple front matter formats:

  • Standard YAML (--- delimiters) and TOML (+++ delimiters)
  • Comment-wrapped formats for R and Python files (# and #' prefixes)
  • PEP 723 Python inline script metadata

• Fast C++ parsing with graceful handling of incomplete front matter.

• Flexible parser integration: by default uses yaml12::parse_yaml() and tomledit::parse_toml() or you can provide custom parsers.