MRI Internals: How Ruby Arrays Became a VM Playground

May 12, 2026 If you still think Ruby’s Array is “just a C struct with some methods on top,” you’re about 5 years out of date. Modern MRI tells a very different story. Today, Array sits at the intersection of: Ruby code (array.rb) VM intrinsics (Primitive.*) C runtime (array.c) JIT specialization (YJIT) And the result … Continue reading MRI Internals: How Ruby Arrays Became a VM Playground