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yarutsk

AI-authored

This library — design, implementation, tests, and documentation — was written by Claude Code (Anthropic) under human direction.

A Python YAML library that round-trips documents while preserving comments, insertion order, scalar styles, tags, anchors and aliases, blank lines, and explicit document markers.

Most YAML libraries silently drop comments on load. yarutsk keeps them attached to their keys — both inline (key: value # like this) and block-level (# above a key) — so a load → modify → dump cycle leaves the rest of the file intact.

import io
import yarutsk

doc = yarutsk.load(io.StringIO("""
# database config
host: localhost  # primary
port: 5432
"""))

doc["port"] = 5433

out = io.StringIO()
yarutsk.dump(doc, out)
print(out.getvalue())
# # database config
# host: localhost  # primary
# port: 5433

YamlMapping is a subclass of dict and YamlSequence is a subclass of list, so they work everywhere a dict or list is expected — including json.dumps, isinstance(x, dict), and any library that accepts plain mappings or sequences.

What's preserved

  • Scalar styles — plain, 'single-quoted', "double-quoted", literal block |, folded block >
  • Non-canonical scalars — yes/no/on/off, ~, Null, True/False, 0xFF, 0o77 — reproduced as written, not re-canonicalised
  • YAML tags — !!str, !!python/tuple, and any custom tag are emitted back verbatim
  • Anchors and aliases — &name on the anchor node and *name for references; the Python layer returns the resolved value transparently
  • Blank lines between mapping entries and sequence items
  • Explicit document markers — --- and ...

Where to go next

Source: https://github.com/theyugin/yarutsk