node

@mettascript/node

Node.js entry for MeTTaScript: the metta command-line interface, file-based import!, and a SharedArrayBuffer worker-thread parallel matcher. Re-exports everything from @mettascript/core.

Install

npm install @mettascript/node
# for the CLI on your PATH:
npm install -g @mettascript/node

CLI

metta is a single command with subcommands:

metta run program.metta       # run a program (metta program.metta is shorthand)
metta check program.metta     # static analysis (--json, --undefined-symbols)
metta debug --file program.metta why '(main)'   # engine debugger (why/eval/run)
metta graph program.metta -o out.gif            # render the reduction as an animated GIF
metta --version

Without a global install: npx -p @mettascript/node metta run program.metta.

Host runtimes are explicit and lazy:

metta run --py program.metta       # Python through pythonia
metta run --prolog program.metta   # Prolog through a local swipl executable

Without those flags the CLI never loads Python, Prolog, or their optional dependencies. metta graph similarly loads @mettascript/grapher and its renderers only when invoked; install them with npm install @mettascript/grapher gifenc sharp.

The earlier metta-ts (run) and metta-debug (debug) commands remain as aliases, so existing scripts keep working.

Usage

import { runFile, ParallelFlatMatcher } from "@mettascript/node";

// Run a .metta file (resolves import! against the file system).
for (const { query, results } of runFile("program.metta")) {
  console.log(query, results);
}

ParallelFlatMatcher scans a large flat knowledge base across worker_threads over a shared token buffer. It pays off only for a large KB scanned by a non-selective query whose result set is small; a keyed query is already near-constant-time via the in-memory argument index.

License

MIT.