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bend: wire bend!-call into the pyodide tier — playground python ⚡

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lumbda-py.js (and the three deployed mirrors) now expose setBendUrl
and register a bend!-call primitive in the pyodide-hosted lumbda
environment.

Implementation:
  - JS loader stashes a `globalThis._lumbdaPyBendCall` function that
    does sync XHR POST to the configured bend URL (legal in Web
    Workers, where the pyodide tier runs in this playground)
  - Python bootstrap imports `_lumbdaPyBendCall` from `js` and binds
    it as a builtin under the symbol `bend!-call`, accepting any
    value and stringifying via lumbda.show before sending
  - setBendUrl(url) on the tier object updates the JS closure; the
    runner.js plumbing already calls it on every tier when the user
    saves a bend URL in the ⚡ bar

This brings the pyodide tier to parity with the asm (WAT) tier for
HTTP-mode bend. The emcc C tier still lacks the bind — wiring it
needs a new wasm primitive built via emcc; lands in the next commit.

Tested: bend!-call "(ping)" against the same gpu-worker endpoint
returns the same (ok pong) S-expression the asm tier sees.
This commit is contained in:
russell@unturf.com 2026-06-14 18:25:46 -04:00
parent 755a4f42ef
commit 11470a5fba
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4 changed files with 140 additions and 4 deletions
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36
wasm/python/lumbda-py.js
View file

@ -2,7 +2,9 @@
// Python tier loader — Pyodide (CPython-in-WASM) hosting lumbda.py.
//
// ES module form so it works in both window and Web Worker contexts.
// Exports createPythonTier() -> Promise<{ evalLisp(src) -> Promise<string> }>.
// Exports createPythonTier() -> Promise<{ evalLisp(src) -> Promise<string>,
// setBendUrl(url) -> void,
// heapStats() -> {used,total} }>.
const PYODIDE_VERSION = "0.27.2";
const PYODIDE_INDEX_URL = `https://cdn.jsdelivr.net/pyodide/v${PYODIDE_VERSION}/full/`;
@ -22,6 +24,25 @@ async function _bootstrap() {
pyodide.FS.writeFile("/home/pyodide/lumbda.py", lumbdaSrc);
pyodide.FS.writeFile("/home/pyodide/stdlib.lsp", stdlibSrc);
// bend dispatch closure. Browser can't open raw TCP, so we POST
// the S-expression payload to the configured worker URL and read
// the response text back. Sync XHR is the only sync HTTP available
// in a Web Worker; perfect for the blocking eval model lumbda
// primitives expect.
const refs = { bendUrl: null };
globalThis._lumbdaPyBendCall = (payload) => {
if (!refs.bendUrl) return "no bend URL configured";
try {
const xhr = new XMLHttpRequest();
xhr.open("POST", refs.bendUrl, false); // sync
xhr.setRequestHeader("Content-Type", "text/plain; charset=utf-8");
xhr.send(payload);
return xhr.responseText || "";
} catch (e) {
return `bend error: ${e.message || String(e)}`;
}
};
await pyodide.runPythonAsync(`
import sys, io
sys.path.insert(0, "/home/pyodide")
@ -30,6 +51,18 @@ _env = lumbda.make_global_env()
for _e in lumbda.read_all(lumbda.PRELUDE):
lumbda.leval(_e, _env)
# bend!-call primitive — bridges to JS XHR via globalThis._lumbdaPyBendCall.
# Argument: a string payload (the S-expression text). Returns response text.
from js import _lumbdaPyBendCall as _js_bend_call
def _bend_call_prim(args, env):
if not args:
return ""
payload = args[0]
if not isinstance(payload, str):
payload = lumbda.show(payload)
return str(_js_bend_call(payload))
_env.define(lumbda.S('bend!-call'), _bend_call_prim)
def _lumbda_eval(src):
buf = io.StringIO()
old = sys.stdout
@ -56,6 +89,7 @@ def _lumbda_eval(src):
pyodide.globals.set("_src_in", src);
return await pyodide.runPythonAsync("_lumbda_eval(_src_in)");
},
setBendUrl(url) { refs.bendUrl = url || null; },
heapStats() {
// Pyodide's runtime memory is the Emscripten linear memory.
// CPython's GC reclaims behind the scenes, so this number