dart_monty_core

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dart_monty_core 0.120.1 · monty 1.2.0

dart_monty_core runs Python in Dart through pydantic-monty, a sandboxed Python interpreter written in Rust. Dart programs can provide typed inputs, host functions, host modules, OS operations, host-directory mounts, resource limits, and type checking. Results return as typed MontyValue objects.

Dart applications cannot load new behavior without shipping a new binary. Monty lets an application run supplied Python under resource limits while exposing only selected host functions, host modules, and OS operations. Pydantic runs a security bug bounty for the interpreter at hackmonty.com.

Each session runs outside the application process. Native sessions use child processes, and browser sessions use Web Workers. A sandbox crash ends its worker and session without ending the application. The pool replaces the worker for a later checkout.

Installation

dart pub add dart_monty_core

Quick start

import 'package:dart_monty_core/dart_monty_core.dart';

Future<void> main() async {
  final value = await Monty.withPool(
    (monty) => monty.withSession((session) async {
      await session.feedRun(
        'def fib(n): return n if n < 2 else fib(n - 1) + fib(n - 2)',
      );
      return session.feedRun('fib(10)');
    }),
  );
  print(value); // MontyInt(55)
}

The example evaluates Fibonacci in a pooled session.

Platform support

See Native worker for native worker setup, browser asset serving, caching, integrity checks, Flutter packaging, and platform details.

Host-directory mounts require the native mount library and are unavailable in browsers. OSAccess provides an in-memory filesystem on every platform.

Documentation

• Documentation index
• Execution model
• Host functions and async
• Host modules
• OS access
• Host directory mounts
• Telemetry
• Fake sessions
• Upstream divergences and limitations
• Package versioning

The API reference documents values, errors, snapshots, limits, callbacks, and session methods. The package exports test doubles from package:dart_monty_core/dart_monty_core_testing.dart and host-backed virtual files from package:dart_monty_core/unsafe_callback_file.dart.

Contributor commands and repository rules are in AGENTS.md.

License

MIT.