MeTTaMeTTa, in pure TypeScript

A complete implementation of the OpenCog Hyperon language that runs in the browser, Node, Deno, Bun, edge functions, and TypeScript AI agents. No native addons, no required WASM.

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Learn MeTTa

GitHub

MeTTaGrapher playing a generate-and-test search, where candidate selections fan out, are tested, and prune to the answers

Run it anywhere

One core ESM bundle, ~23 KB gzipped. No native addon, no required WASM, no Rust. Import it in a web page, a serverless handler, or an agent loop and go.

Faithful semantics

A port of hyperon-experimental's minimal interpreter, validated 270/270 against Hyperon's oracle corpus and cross-checked against the Lean-verified LeaTTa semantics.

TypeScript-native interop

Call your TypeScript functions from MeTTa, drop TypeScript objects straight into the atomspace as grounded atoms, and write rules with a typed eDSL. No FFI, same language end to end.

Optional host runtimes

Opt into Python or Prolog only when you need them. Node adapters use pythonia and SWI-Prolog; browser adapters use Pyodide and SWI-WASM through the same host-import contract.

Async and concurrent

Grounded operations can do I/O and the evaluator awaits them. Concurrency primitives (par, race, once, with-mutex) and transactions build on top.

Scales to millions of atoms

Prolog-style clause indexing keys queries by functor and every ground argument, plus a flat interned KB with a worker-thread parallel matcher.

A typed eDSL

Write MeTTa in idiomatic TypeScript with typed term builders and a tagged template. Optional helper subpaths build Python and Prolog interop calls without loading those runtimes.