dspy-monty-interpreter 0.2.0

DSPy CodeInterpreter implementation using Monty, a secure Python interpreter written in Rust

dspy-monty-interpreter

DSPy CodeInterpreter implementation using Monty, a secure Python interpreter written in Rust.

The Monty team points out, "This project is still in development, and not ready for the prime time." It uses a small subset of the standard library (sys, os, typing, asyncio, re, datetime, json) and can't yet define classes or use match statements.

That said: Monty is fast. For many RLM use cases, Monty is my daily driver.

Installation

pip install dspy-monty-interpreter

Requires pydantic-monty>=0.0.10.

Usage

import dspy
from dspy_monty_interpreter import MontyInterpreter

interpreter = MontyInterpreter()
rlm = dspy.RLM("context -> answer", interpreter=interpreter)
result = rlm(context="What is 2 + 2?")

Standalone usage

from dspy_monty_interpreter import MontyInterpreter

interp = MontyInterpreter()

# Basic execution
interp.execute("x = 42")
interp.execute("print(x + 8)")  # returns "50"

# State persists across calls
interp.execute("def double(n):\n    return n * 2")
interp.execute("double(21)")  # returns "42"

# With tools
def lookup(key: str) -> str:
    return "some value"

interp = MontyInterpreter(tools={"lookup": lookup})
interp.execute('result = lookup(key="foo")\nprint(result)')

Filesystem mounts

Filesystem access is disabled by default. Use mounts= to expose a host directory to sandboxed code under a virtual path:

from dspy_monty_interpreter import MontyInterpreter, MountDirectory

# Read-only mount: sandbox can read but not write
interp = MontyInterpreter(
    mounts=MountDirectory("/data", "/host/path/to/data", mode="read-only")
)
interp.execute("from pathlib import Path\nPath('/data/input.csv').read_text()")

# Overlay mount: reads fall through to host; writes stay in memory
interp = MontyInterpreter(
    mounts=MountDirectory("/work", "/host/project", mode="overlay")
)

Modes: "read-only", "read-write", "overlay". Pass a list of MountDirectory for multiple mount points.

Why Monty?

• Fast: Microsecond startup (no subprocess, no WASM bootstrap)
• Secure: No network or environment access; filesystem access is opt-in via mounts
• Lightweight: Pure Rust, no Deno/Pyodide dependency