lumbda/www/playground/demos/fib-ack.lsp
russell@unturf.com 1b7de2c9c6
wasm/playground: cancel button, asm state-leak fix, restyle to match homepage
User-visible changes
  - Cancel button — terminates the running worker. Pyodide's slow mandelbrot
    no longer freezes the UI; click cancel and the elapsed counter freezes
    at "(cancelled @ NNNN ms)".
  - Live ms counter ticks per animation frame while a tier is busy, so the
    Pyodide tier's ~5-15 s wait is visible instead of looking hung.
  - Restyled to match lumbda.com: chunkfive wordmark, --green: #227842
    (light) / #5ec07a (dark), lumbda-logo-green.png, lowercase "lumbda"
    everywhere. Pulls fonts/chunkfive locally so the playground stays
    self-contained.

Architecture
  - All tier evaluations now run inside a Web Worker (wasm/app/worker.mjs)
    so the main thread stays responsive. Cancel = worker.terminate(); next
    eval respawns a fresh worker.
  - Loaders use new URL("./...", import.meta.url) so paths resolve against
    the loader file's own location — works identically in window and
    worker contexts, no baseURL argument needed.
  - C tier Emscripten build flipped to EXPORT_ES6=1; loader uses dynamic
    `import()` of the factory module. Integration test updated accordingly.
  - Python loader uses `import("pyodide.mjs")` (ES module) instead of
    document.createElement, which doesn't exist in workers.

Bug fixes
  - Asm tier state leak: running the same demo twice on a cached WASM
    instance produced corrupted output (every other cell on row 2+ rendered
    as " " instead of the expected shade char). Root cause: top-level eval
    passed `global_env` as the env, so closures captured stale globals;
    fixed by passing NIL — env_lookup falls back to the CURRENT global_env
    via its existing two-pass walk. Multi-run regression added to the
    functional test suite.
  - fib-ack demo: (ack 3 4) was too heavy for Pyodide (minutes). Cut to
    (ack 3 3) + (fib 20) max so every tier finishes in seconds.

Test discipline
  - Root `make test-all` now includes `wasm-test`. Adding a language
    feature without exercising it on all six implementations is no longer
    possible by accident.
  - Functional suite: 11 assertions (was 10) — adds asm multi-run stability.
  - Integration + unit: still 20 + 8.
2026-06-14 12:13:20 -04:00

20 lines
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Text

; Fibonacci + Ackermann — the classic recursion duo.
; Tests deep recursion across all three tiers.
(define (fib n)
(if (< n 2) n
(+ (fib (- n 1)) (fib (- n 2)))))
(define (ack m n)
(cond ((= m 0) (+ n 1))
((= n 0) (ack (- m 1) 1))
(else (ack (- m 1) (ack m (- n 1))))))
; Demo deliberately stays small so Pyodide finishes in a few seconds.
; (ack 3 4) is 125 but takes minutes via CPython-in-WASM tree-walker;
; cut down to (ack 3 3) so every tier can run it.
(display "fib(15) = ") (print (fib 15))
(display "fib(20) = ") (print (fib 20))
(display "ack(2,3) = ") (print (ack 2 3))
(display "ack(3,3) = ") (print (ack 3 3))
(print "done")