README.md

@mettascript/browser

Browser entry for MeTTaScript. Re-exports everything from @mettascript/core and adds an in-memory virtual file system so import! works without disk access.

Install

npm install @mettascript/browser

Usage

import { run, runSourceAsync } from "@mettascript/browser";

// A virtual file system: module name -> MeTTa source.
const files = new Map([["math", "(= (double $x) (* 2 $x))"]]);

const results = run(
  `
  !(import! &self math)
  !(double 21)
`,
  files,
);

run(src, files?, fuel?) evaluates a program, resolving import! against the in-memory files. The whole interpreter is pure TypeScript, so it runs in any browser with no native addon and no required WASM.

For embedders that already resolved imports, @mettascript/browser/source exposes source runners:

import { runSourceAsync } from "@mettascript/browser/source";

const results = await runSourceAsync(`
  !(import! &self concurrency)
  !(par (+ 1 1) (+ 2 2))
`);

The async runner supports MeTTa's async forms (par, race, with-mutex) and uses Web Workers for (once (hyperpose ...)) when the browser host provides them.

Host Interop

@mettascript/browser/host composes optional host runtimes such as Pyodide and SWI-Prolog WASM. The base browser package stays pure TypeScript. Import a host adapter only when the page needs it.

import { createBrowserRunner, createBrowserTextLoader } from "@mettascript/browser/host";
import { createPyodideInterop } from "@mettascript/py/pyodide";
import { createSwiWasmInterop } from "@mettascript/prolog/swi-wasm";

const files = new Map([
  ["math.py", "def add(a, b):\n    return a + b\n"],
  ["facts.pl", "edge(alice, bob).\n"],
]);
const loadText = createBrowserTextLoader({ files, baseUrl: import.meta.url });
const py = await createPyodideInterop({ loadText });
const prolog = await createSwiWasmInterop({ loadText });
const runner = createBrowserRunner({ files, interops: [py, prolog] });

const results = await runner.run(`
  !(import! &self "math.py")
  !(py-call (math.add 40 2))
  !(import! &self "facts.pl")
  !(prolog-call (edge alice $x))
`);

await runner.dispose();

See examples/browser-interop for a runnable smoke check and a bundle isolation check.

License

MIT.