npm install @pydantic/monty

import { Monty } from '@pydantic/monty'

// Create interpreter and run code
const m = new Monty('1 + 2')
const result = m.run() // returns 3

const m = new Monty('x + y', { inputs: ['x', 'y'] })
const result = m.run({ inputs: { x: 10, y: 20 } }) // returns 30

const m = new Monty('add(2, 3)')

const result = m.run({
  externalFunctions: {
    add: (a: number, b: number) => a + b,
  },
}) // returns 5

import { Monty, runMontyAsync } from '@pydantic/monty'

const m = new Monty('fetch_data(url)', {
  inputs: ['url'],
})

const result = await runMontyAsync(m, {
  inputs: { url: 'https://example.com' },
  externalFunctions: {
    fetch_data: async (url: string) => {
      const response = await fetch(url)
      return response.text()
    },
  },
})

const m = new Monty('a() + b()')

let progress = m.start()
while (progress instanceof MontySnapshot) {
  console.log(`Calling: ${progress.functionName}`)
  console.log(`Args: ${progress.args}`)
  // Provide the return value and resume
  progress = progress.resume({ returnValue: 10 })
}
// progress is now MontyComplete
console.log(progress.output) // 20

import { Monty, MontySyntaxError, MontyRuntimeError, MontyTypingError } from '@pydantic/monty'

try {
  const m = new Monty('1 / 0')
  m.run()
} catch (error) {
  if (error instanceof MontySyntaxError) {
    console.log('Syntax error:', error.message)
  } else if (error instanceof MontyRuntimeError) {
    console.log('Runtime error:', error.message)
    console.log('Traceback:', error.traceback())
  } else if (error instanceof MontyTypingError) {
    console.log('Type error:', error.displayDiagnostics())
  }
}

const m = new Monty('"hello" + 1')
try {
  m.typeCheck()
} catch (error) {
  if (error instanceof MontyTypingError) {
    console.log(error.displayDiagnostics('concise'))
  }
}

// Or enable during construction
const m2 = new Monty('1 + 1', { typeCheck: true })

const m = new Monty('1 + 1')
const result = m.run({
  limits: {
    maxAllocations: 10000,
    maxDurationSecs: 5,
    maxMemory: 1024 * 1024, // 1MB
    maxRecursionDepth: 100,
  },
})

// Save parsed code to avoid re-parsing
const m = new Monty('complex_code()')
const data = m.dump()

// Later, restore without re-parsing
const m2 = Monty.load(data)
const result = m2.run()

// Snapshots can also be serialized
const snapshot = m.start()
if (snapshot instanceof MontySnapshot) {
  const snapshotData = snapshot.dump()
  // Later, restore and resume
  const restored = MontySnapshot.load(snapshotData)
  const result = restored.resume({ returnValue: 42 })
}