How to use Asynchronous Comprehensions?

Question

I\'m trying to use Python 3.6\'s async comprehensions in a MacOS Sierra (10.12.2), but I\'m receiving a SyntaxError.

Here is the code I\'ve tried:

Answer 1

This behaves as expected. The issue is that these forms of comprehensions are only allowed inside async def functions. Outside (i.e in the top-level as entered in your REPL), they raise a SyntaxError as defined.

This is stated in the specification section of the PEP, specifically, for asynchronous comprehensions:

Asynchronous comprehensions are only allowed inside an async def function.

Similarly, for using await in comprehensions:

This is only valid in async def function body.

As for async loops, you'll need both an object that conforms to the necessary interface (defines __aiter__) and placed inside an async def function. Again, this is specified in the corresponding PEP:

It is a TypeError to pass a regular iterable without __aiter__ method to async for. It is a SyntaxError to use async for outside of an async def function.