22,488 examples pass in ruby/spec's language/ + core/ suites, measured 2026-09-26 on main (3e8e3cc). Three independent runs — two through the ratchet at different timeouts, one through a separate sweep — reported the same total.
core/random/bytes_spec.rb) is unstable between 8 and 9 passing examples; since 2026-11-04 its row holds 8, its floor, because a row recorded at the high draw makes the next ordinary run a red build. This replaced a single shrink-only floor of 22,475, which needed a margin wider than the largest spec file and so could not see a regression smaller than that.language/ and core/ are swept. ruby/spec's library/, optional/ and security/ trees are not run at all, so this figure is not a percentage of Ruby, and most of the standard library sits outside it.language/ and core/ are swept. ruby/spec's library/, optional/, command_line/ and security/ trees are not run at all, so this figure is not a percentage of Ruby, and most of the standard library sits outside it.ruby_exe, ruby_cmd and output_to_fd — three helpers that would need a subprocess or real file-descriptor redirection — and 10 of 2,206 spec files produce no result. Skips and unreadable files sit outside the ratio entirely.A real object model — classes, mixins, method_missing, metaprogramming, Fiber. The Go API is deliberately small today: ruby.Run(src, out) runs a program on a fresh VM and writes its output to one writer. Calling a Ruby method from Go is not exposed yet.
CGO=0 by default. Tested on amd64, arm64, riscv64, loong64, ppc64le, s390x, 386 and arm; compiles for every GOOS/GOARCH Go supports — 47 targets, the BSDs, AIX, Solaris, mips and Plan 9 included (Plan 9 is vetted, not run).
Ahead-of-time compilation of integer-bound methods to unboxed Go. Measured on this project’s own micro-benchmarks (darwin/arm64, whole-process wall time): 8.7× MRI+YJIT on the tight-loop case, 2.0× on recursive fib(35). Only methods the compiler can lower benefit.
23,672 ruby/spec language/ + core/ examples pass, gated in CI file by file: no spec file may pass fewer examples than its recorded row, so a regression is named rather than absorbed in a total. Only language/ and core/ are swept: library/, optional/ and security/ are not run, so this is not a percentage of Ruby. Those guards now resolve at Ruby 4.0.9 — the version this runtime reports, and the latest MRI release — so the examples behind a ruby_version_is "4.0" guard are counted, and those behind ruby_version_is ""..."4.0" are no longer asked for. The move was measured before it was made, both engines built from one commit minus the version string: +144 passing, and 27 examples that went red — a figure no pass total shows, found by comparing the two runs' failure descriptions. Front-end: ~100% of valid Ruby parsed across Rails + Puppet (2026-06).
23,672 ruby/spec language/ + core/ examples pass, gated in CI file by file: no spec file may pass fewer examples than its recorded row, so a regression is named rather than absorbed in a total. Only language/ and core/ are swept: library/, optional/, command_line/ and security/ are not run, so this is not a percentage of Ruby. Those guards now resolve at Ruby 4.0.9 — the version this runtime reports, and the latest MRI release — so the examples behind a ruby_version_is "4.0" guard are counted, and those behind ruby_version_is ""..."4.0" are no longer asked for. The move was measured before it was made, both engines built from one commit minus the version string: +144 passing, and 27 examples that went red — a figure no pass total shows, found by comparing the two runs' failure descriptions. Front-end: ~100% of valid Ruby parsed across Rails + Puppet (2026-06).
rbgo build --closed bakes the program to bytecode and drops the front-end for a smaller binary.
Built from the go-ruby-* family — each a 100%-coverage, 6-arch stdlib module, bound natively.