Getting started

Ever used asyncio and wished you hadn't?

tinyio is a tiny (~400 lines) event loop for Python, born out of frustration with trying to get robust error handling with asyncio. (link1, link2.)

This is an alternative for the simple use-cases, where you just need an event loop, and want to crash the whole thing if anything goes wrong. (Raising an exception in every coroutine so it can clean up its resources.)

Installation

pip install tinyio

Requires Python 3.11+.

Quick example

import tinyio

def slow_add_one(x: int):
    yield tinyio.sleep(1)
    return x + 1

def foo():
    four, five = yield [slow_add_one(3), slow_add_one(4)]
    return four, five

loop = tinyio.Loop()
out = loop.run(foo())
assert out == (4, 5)

Somewhat unusually, our syntax uses yield rather than await, but the behaviour is the same. Await another coroutine with yield coro. Await on multiple with yield [coro1, coro2, ...] (a 'gather' in asyncio terminology; a 'nursery' in trio terminology).

An error in one coroutine will cancel all coroutines across the entire event loop.

• If the erroring coroutine is sequentially depended on by a chain of other coroutines, then we chain their tracebacks for easier debugging.
• Errors propagate to and from synchronous operations ran in threads.

Can nest tinyio loops inside each other, none of this one-per-thread business.

Ludicrously simple. No need for futures, tasks, etc. Here's the entirety of the day-to-day API:

• tinyio.Loop
• tinyio.CancelledError
• tinyio.sleep
• tinyio.run_in_thread

Next steps

Check out the coroutines and loops page.