Standard library modules

Monty ships a fixed set of built-in stdlib modules. import of anything else raises ModuleNotFoundError: there is no sys.path, no site-packages, and no way for sandboxed code to load additional modules.

Every import builds a fresh module object; there is no sys.modules cache. So two imports of the same module are not the same object (import math as a; import math as b leaves a is not b), and a mutable attribute reverts on the next import — sys.argv.append(...) is not seen by a later import sys. Module attributes cannot be set at all (sys.x = 1 raises AttributeError), so there is no way to share state through a module. The one exception is random’s module-level generator, which is session state: a random.seed(...) is still in effect after a later import random, in the next feed, and after a dump (see random.md).

Modules available

Module	See
asyncio	asyncio.md
base64	base64.md
binascii	base64.md
collections	collections.md
copy	copy.md
dataclasses	dataclasses.md
datetime	datetime.md
functools	functools.md
itertools	itertools.md
json	json.md
math	math.md
os	os.md
pathlib	pathlib.md
random	random.md
re	re.md
sys	sys.md
time	time.md
typing	typing.md
unicodedata	unicodedata.md

collections is importable and exposes deque, Counter, defaultdict, and namedtuple; OrderedDict, ChainMap, and the UserDict / UserList / UserString wrappers are missing (see collections.md).

A gc module exposing collect() / enable() / disable() is compiled in only under the test-hooks Cargo feature, for Monty’s own test suite; production sandboxes never see it.

Notable modules NOT available

Common modules that are not importable in Monty (non-exhaustive): abc, argparse, array, bisect, contextlib, csv, ctypes, decimal, enum, fractions, hashlib, heapq, hmac, http, inspect, io, logging, multiprocessing, operator, pickle, queue, socket, string, struct, subprocess, tempfile, threading, traceback, unittest, urllib, uuid, warnings, weakref, zipfile, zlib.

socket, subprocess, multiprocessing, threading and ctypes are excluded because they would breach the sandbox. Others (enum, operator) are unimplemented and may appear over time.

Some available modules cover only part of their CPython surface: functools implements only reduce and partial, copy only copy() and deepcopy(), time everything but tzset and the clock_* family, and collections only the four types above. The absent names are missing from the module namespace rather than stubbed, so they fail type checking as well as raising AttributeError at runtime; see each module’s page for the specifics.

Modules the type checker resolves but the runtime does not

abc, types, typing_extensions, _collections_abc and _typeshed back the vendored stubs (e.g. @abstractmethod on protocol members), so they have to resolve during type checking. Importing them therefore type-checks clean but still raises ModuleNotFoundError at runtime.