[FIXED] Use `any` with an `async_generator` Inside a Generator Expression

Issue

If I have a regular iterable object in Python I can use any and a generator comprehension to get boolean. E.g.

from pathlib import Path

path = Pathlib("/foo/bar/baz")
has_contents = any(path.iterdir())

And I can do the same thing with an async_generator and list comprehension:

is_empty = any([x async for x in async_generator])

But it doesn't seem to be possible to do the same with an async_generatorand a generator comprehension.

not_empty = any(x async for x in foo.iter())

raises

TypeError: 'async_generator' object is not iterable

Is there a way to use an async_generator inside a generator comprehension?

Solution

The problem is not using an async_generator in a generator comprehension. That part is fine.

>>> async def ag():
...     yield 0
...     yield 1
... 
>>> (x async for x in ag())
<async_generator object <genexpr> at 0x7fffe34fd640>

The issue is consuming an async generator with a function that expects a synchronous iterator.

In this case, you can't iterate it with the regular for x in ... syntax, and you shouldn't pass it to functions that expect a synchronous iterator, such as any. You'll see the same problem with list(...).

Answered By - wim