MEP-56 note 03: Prior-art transpilers

Author: research pass for MEP-56 (Mochi to Ruby transpiler). Date: 2026-05-29 (GMT+7).

Survey of Opal (Ruby-to-JavaScript), RubyMotion (Ruby-to-native iOS/Android), Crystal (statically typed Ruby-like), mruby (embeddable Ruby), JRuby (JVM Ruby), TruffleRuby (GraalVM Ruby), Artichoke (Rust-hosted mruby). Lessons applied to MEP-56 rtree design.

Full research note content for MEP-56 note 03.