Thanks for your reply.
> What's the advantage?
I brought this up thinking about explicitness and readability. Say you want to
figure out what this function is doing:
````
def foo() -> t.Iterator[T]:
[... 300 lines of code]
```
Is this a generator function? I'd argue that whether it's a generator function
or not is fundamental to being able to read it. The type hint alone doesn't
tell you whether you're looking at a generator function or not - it might just
construct and return an iterator.
So, you have to look for a `yield`. And if "yield" is somewhere in the function
body, it will abruptly change the semantics of the entire definition. This
feels a like spooky-action-at-a-distance to me - I'd much rather have the
information up top in the function declaration, the same way that `async def`
declares a coroutine function.
However: this was actually discussed in PEP 255, where there was a decision
*not* to introduce a new keyword for generator functions. From the BDFL
decision:
> No argument on either side is totally convincing, so I have consulted
> my language designer’s intuition. It tells me that the syntax proposed
> in the PEP is exactly right - not too hot, not too cold. But, like the Oracle
> at Delphi in Greek mythology, it doesn’t tell me why, so I don’t have a
> rebuttal for the arguments against the PEP syntax.
- Aaron
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