Another creation of @kddnewton, psych-pure is a pure-Ruby YAML 1.2 parser library. While we already have excellent YAML 1.2 support via SnakeYAML Engine (used to power our version of the psych gem), this would be a good opportunity to explore pure-Ruby performance in JRuby and find optimization opportunities.

Blog post here: https://kddnewton.com/2025/12/25/psych-pure.html