playground: a Ruby tab, run in the browser by go-embedded-ruby

[tannevaled]

The code panel gains a Ruby program between Go and NumPy (tabs Go | Ruby | NumPy), and Run executes it in the page with go-embedded-ruby compiled to WebAssembly.

What changes

• engine: every operation in Ops gets a Ruby spelling (plan.rb, Step.Rb, Session.RbProgram(sel)), written against go-embedded-ruby's NDArray API: NDArray.arange/linspace/zeros/ones/full/eye/from, a.reshape(3, -1), a.transpose, a.dup, NumPy slices as Ranges and ArithmeticSequences (b[true, (1..) % 2], b[(-1..) % -1]), a.sum(1, keepdims: true), NDArray.maximum(a, b), a.matmul(b), NDArray.concatenate([a, b], axis: 0), ... engine/ruby_test.go checks each spelling and that it calls nothing outside that API. The program prints every step, then the selected step's shape and to_a.
• vm: LangRuby, a RunRuby command, RubyStatus/RubyProgress/RubyOutput observables, and two host hooks (RubyLoad, RubyEval). The interpreter is requested the first time the Ruby tab is opened; Run pressed during the download runs after it; a failed download can be retried.
• View: Run beside Copy, the program beside its output (below it on a phone), a status line and a progress bar for the download, and a Ruby detail line.
• Page: ndarrayRubyLoad(onProgress) fetches /playground/rbgo.wasm (byte-counted progress, size read at build time) and starts it in a second new Go().
• Build: playground/rubywasm/ is a module of its own that pins github.com/go-embedded-ruby/ruby through a tool directive (Renovate bumps it). The deploy builds cmd/wasm from it with -trimpath -ldflags="-s -w", with the same toolchain as the playground, so one wasm_exec.js serves both modules.

Size

The go-embedded-ruby wasm is about 99 MB stripped (21 MB gzipped) against 13.9 MB for the playground, so the page never loads it up front: only when the Ruby tab is opened.

Proof

TestBrowserProof counts requests for rbgo.wasm: none through the Go and NumPy tabs, one when the Ruby tab opens, still one after two runs. It runs the README example in Ruby and requires the printed shape and to_a to equal go-ndarray's result for the same step (desktop light@1x and the phone). Negative control, run locally: making the page fetch the Ruby wasm at start-up fails the proof at "the Ruby module was not downloaded before the Ruby tab was opened".

go-embedded-ruby v0.5.0

rubywasm/go.mod pins v0.5.0 (3c86317, the merge of go-embedded-ruby#813, which implements the NDArray API), on go-ndarray v0.11.0 like the playground. v0.3.0 and v0.4.0 lack the binding. Stripped wasm: 99,921,220 bytes, 21,396,357 gzipped (102,598,409 unstripped).

TestRubyAgreesWithGo (engine) runs the Ruby program of every operation case and of every preset step, 111 programs, on the interpreter under node, and compares the printed shape and values with go-ndarray's numerically. Against v0.3.0 it reports 98 failures. With a deliberate off-by-one in the Ruby spelling of 1:, it fails on Slice(1:, ::-1).

🤖 Generated with Claude Code