Upgrading YAML spec from 1.1 to 1.2?

[ickc]

by switching dependency from pyyaml to ruamel.yaml.

Not actionable for now as we should wait for a final decision from upstream. c.f. https://github.com/jgm/pandoc/issues/4535

TL;DR: pandoc switch from YAML 1.1 to 1.2 recently, but option is still open to revert that change. If the final decision is to stay with HsYAML with YAML 1.2 spec, then I think we should migrate to YAML 1.2 too to have a more uniform YAML experience (e.g. YAML codeblock in panflute do our own YAML parsing.)

ruamel.yaml is a fork of pyyaml, which also has a fork of libyaml which implements YAML 1.2. ruamel.yaml has a different API recently, but shouldn't be a big problem. Also, it has widely been used and supported, e.g. in conda-forge both share the same support across platforms. In my own testing ruamel.yaml is about a factor of 2 slower than pyyaml, and both grows roughly linear time.

More info (copy from my https://github.com/jgm/pandoc/issues/4535#issuecomment-748020730):

• a commit that switch from yaml to HsYAML: Use HsYAML instead of yaml for translations, YAML metadata. · jgm/pandoc@e49b830
• Haskell lib info:
  • yaml: Support for parsing and rendering YAML documents.
  • HsYAML: Pure Haskell YAML 1.2 processor
• Note on YAML verison:
  • yaml has YAML 1.1 spec: 2005-01-18: YAML Ain’t Markup Language (YAML™) Version 1.1
  • HsYAML has YAML 1.2 spec: 2009-10-01: YAML Ain’t Markup Language (YAML™) Version 1.2
• to yaml or HsYAML?
  • 2020-2-13: https://github.com/jgm/pandoc/issues/6084#issuecomment-585838371 seem to indicate @jgm want to go back from HsYAML to yaml
  • 2020-7-30: https://github.com/jgm/pandoc/issues/4535#issuecomment-666948352 seem to indicate @jgm want to stick to the plan of removing non-Haskell dep
  • 2020-12-18: https://github.com/jgm/pandoc/issues/4535#issuecomment-748194457 indicate @jgm is still undecided

Edit: see https://gist.github.com/ickc/f9d6c57338d4be07f6cf70991d462fc3 for a benchmark. (You cannot see the plot using the rendering on GitHub directly.)

[ickc]

Upstream decided to switch bach to YAML 1.1.

See

• https://github.com/jgm/pandoc/issues/6084#issuecomment-952530875
• https://github.com/jgm/pandoc/commit/589887150a3715ac73a951cf7c7513dd08f790a4

[jgm]

Note, no decision has been made yet. We have a PR but it hasn't been merged.